Light emitting diode module for surface mount technology and method of manufacturing the same

ABSTRACT

An LED is provided to include: a first conductive type semiconductor layer; an active layer positioned over the first conductive type semiconductor layer; a second conductive type semiconductor layer positioned over the active layer; and a defect blocking layer comprising a masking region to cover at least a part of the top surface of the second conductive semiconductor layer and an opening region to partially expose the top surface of the second conductive type semiconductor layer, wherein the active layer and the second conductive type semiconductor layer are disposed to expose a part of the first conductive type semiconductor layer, and wherein the defect blocking layer comprises a first region and a second region surrounding the first region, and a ratio of the area of the opening region to the area of the masking region in the first region is different from a ratio of the area of the opening region to the area of the masking region in the second region.

PRIORITY CLAIMS AND CROSS-REFERENCES TO RELATED APPLICATION

This patent application is a continuation of U.S. patent applicationSer. No. 15/823,325 filed on Nov. 27, 2017, which is a continuation ofU.S. patent application Ser. No. 15/377,731 filed on Dec. 13, 2016,which is a continuation of U.S. patent application Ser. No. 15/271,026filed on Sep. 20, 2016, which is a continuation of U.S. patentapplication Ser. No. 14/752,413 filed on Jun. 26, 2015, which is acontinuation-in-part of U.S. patent application Ser. No. 14/588,878filed on Jan. 2, 2015, which is a continuation-in-part of InternationalPCT application number PCT/KR2013/005557 filed on Jun. 24, 2013, whichfurther claims priorities to and benefits of Korean application number10-2012-0071576 filed on Jul. 2, 2012, and Korean patent applicationnumber 10-2014-0079218 filed on Jun. 26, 2014. The entire contents ofthe before-mentioned patent applications are incorporated by referenceherein in their entireties.

TECHNICAL FIELD

This patent document relates to a light emitting diode (LED) including asurface-mount LED module and a method of manufacturing the same. Forexample, the patent document relates to an LED having a structurecapable of minimizing leakage current caused by a defect such aspotential and a method for manufacturing the same.

BACKGROUND

A light emitting diode (LED) is a device including an n-typesemiconductor layer, a p-type semiconductor layer, and an active layerinterposed between the n- and p-type semiconductor layers. When aforward electric field is applied to the n- and p-type semiconductorlayers, electrons and holes may be injected into the active layer andrecombine in the active layer to emit light.

An LED module including a plurality of LEDs is disclosed in, forexample, U.S. Patent Publication No. 2011-0127568. The surface-mount LEDmodule includes a p-type pad and an n-type pad formed on a top surfaceof an LED. However, since the p-type pad is electrically connected tothe entire surface of p-GaN exposed by an insulating layer, currentcrowding may occur.

In addition, depending on the type of a chip, an LED may include areflection layer. For example, the type of a flip-chip is characterizedby emitting light through a substrate. Accordingly, after asemiconductor layer is formed on the substrate, a reflection layerformed of a metal is introduced on the semiconductor layer or a currentspreading layer, and light is reflected by the reflection layer. Also, abarrier layer is provided on the reflection layer. The barrier layer isprovided to prevent diffusion of the metal forming the reflection layer.

SUMMARY

Examples of implementations of the technology disclosed in this patentdocument provide, a light emitting diode (LED), a LED module and amethod of manufacturing an LED module. In some implementations, the LEDmodule proposed in this patent document makes it possible to reducecurrent crowding and maintain its reliability.

In one aspect, a light emitting diode (LED) module is provided toinclude: an LED having a first semiconductor layer, an active layer, asecond semiconductor layer, and a reflection pattern formed on asubstrate, and including a mesa region formed to expose the firstsemiconductor layer, a first insulating layer formed on the mesa regionexposing a portion of a surface of the first semiconductor layer,patterned on the reflection pattern and configured to form a first padregion, a conductive reflection layer formed on the first insulatinglayer and the first semiconductor layer exposed in the mesa region, asecond insulating layer formed on the conductive reflection layer andconfigured to form a second pad region exposing a portion of theconductive reflection layer, a first pad formed on the first pad region,and a second pad formed on the second pad region.

In another aspect, a method of manufacturing an LED module is provided.The method may include: coating a first insulating layer on a structurein which a first semiconductor layer, an active layer, a secondsemiconductor layer, and a reflection pattern are formed on a substrate,forming a first pad region by exposing a portion of the reflectionpattern, and exposing the first semiconductor layer disposed on a mesaregion, forming a conductive reflection layer on the first insulatinglayer, electrically connecting the conductive reflection layer to theexposed first semiconductor layer, and maintaining the first pad regionin an opened state, coating a second insulating layer on the conductivereflection layer to expose the reflection pattern disposed in the firstpad region, and forming a second pad region exposing a portion of theconductive reflection layer electrically connected to the firstsemiconductor layer, and forming a first pad on the first pad region andforming a second pad on the second pad region.

According to some implementations of the disclosed technology, pads areformed on a patterned pad region during manufacture of light emittingdiode (LED) modules. Thus, local current crowding can be prevented.Also, diffusion of metals is prevented due to a reflection barrier layerprovided between a conductive reflection layer and the pads. Forexample, a phenomenon in which a metal forming the conductive reflectionlayer moves to a second pad and increase the resistivity of the secondpad can be prevented. In some implementations, a second semiconductorlayer is electrically connected to a first pad. A pad barrier layer isformed on each of the pads. The pad barrier layer prevents diffusion ofa metal generated during a bonding or soldering process so that thefirst pad or the second pad can have a high conductivity and be inelectrical contact with the outside.

In some implementations, a phosphor layer may be provided on an LED chipand include a plurality of phosphor layers. Accordingly, an operation ofcorrecting color coordinates is enabled using at least one wavelengthconversion operation, and correction of the color coordinates may besimplified by controlling the concentrations of phosphors.

In another aspect, a light emitting diode (LED) is provided to include:a first conductive type semiconductor layer; an active layer positionedover the first conductive type semiconductor layer; a second conductivetype semiconductor layer positioned over the active layer;; a defectblocking layer including a masking region to cover at least a part ofthe top surface of the second conductive semiconductor layer and anopening region to partially expose the top surface of the secondconductive type semiconductor layer; wherein the active layer and thesecond conductive type semiconductor layer are disposed to expose a partof the first conductive type semiconductor layer, and the defectblocking layer may include a first region and a second regionsurrounding the first region, and a ratio of the area of the openingregion to the area of the masking region in the first region isdifferent from a ratio of the area of the opening region to the area ofthe masking region in the second region.

In some implementations, a reflective electrode layer positioned overthe second conductive type semiconductor layer so as to form an ohmiccontact, and covering at least a part of the defect blocking layer; anda first metal layer forming an ohmic contact with the first conductivetype semiconductor layer through the exposed part of the firstconductive semiconductor layer.

According to above LED, the probability that a leakage current andstatic electricity discharge occur can be reduced.

In some implementations, the ratio of the area of the opening region tothe area of the masking region in the first region may be greater thanthe ratio of the area of the opening region to the area of the maskingregion in the second region.

In some implementations, the defect blocking layer may further include athird region surrounding the second region, and the ratio of the area ofthe opening region to the area of the masking region in the secondregion may be greater than the ratio of the area of the opening regionto the area of the masking region in the third region.

In some implementations, the defect blocking layer may further includean additional region surrounding the second region, the first region,the second region, and the additional region may be arranged to beconcentric and have a polygonal shape, and the ratio of the area of theopening region to the area of the masking region may gradually decreasealong an outward direction from the center of the polygonal shape.

In some implementations, the masking region and the opening region ofthe defect blocking layer may be embossed or engraved.

In some implementations, the opening region may be formed to exposeportions of the second conductive type semiconductor layer through aplurality of openings isolated from each other.

In some implementations, the LED further includes a reflective electrodelayer positioned over the second conductive type semiconductor layer soas to form an ohmic contact, and covering at least a part of the defectblocking layer. In some implementations, the plurality of openings maybe covered by the reflective electrode layer, and the reflectiveelectrode layer forms an ohmic contact with the second conductive typesemiconductor layer through the plurality of openings.

In some implementations, the defect blocking layer may be completelycovered by the reflective electrode layer.

In some implementations, a part of the masking region may be covered bythe reflective electrode layer, and the other part of the masking regioncovers at least a part of the second conductive type semiconductorlayer.

In some implementations, the masking region may include a plurality ofmasks isolated from each other.

In some implementations, the LED further comprises a reflectiveelectrode layer positioned over the second conductive type semiconductorlayer so as to form an ohmic contact, and covering at least a part ofthe defect blocking layer.

In some implementations, the plurality of masks may be covered by thereflective electrode layer, and the reflective electrode layer may forman ohmic contact with the second conductive type semiconductor layer.

In some implementations, the masking region and the opening region ofthe defect blocking layer may have a circular pattern or hexagonalpattern.

In some implementations, the defect blocking layer may include aninsulating layer.

In some implementations, the defect blocking layer may include adistributed Bragg reflector.

In some implementations, the LED may further include a plurality ofmesas each including the active layer and the second conductive typesemiconductor layer, wherein the exposed part of the first conductivetype semiconductor layer is located in the peripheral region of theplurality of mesas.

In some implementations, the first and second regions are arranged inthe shape of a concentric rectangle, and the ratio of the area of theopening region to the area of the masking region in the first region isgreater than the ratio of the area of the opening region to the area ofthe masking region in the second region.

In some implementations, the LED may further include a reflectiveelectrode layer positioned over the second conductive type semiconductorlayer so as to form an ohmic contact, and covering at least a part ofthe defect blocking layer, and a lower insulating layer covering theside surfaces of the plurality of mesas and a part of the top surfacesof the plurality of mesas. The lower insulating layer may include afirst opening to expose the first conductive type semiconductor layerand a second opening to partially expose the reflective electrode layer.

In some implementations, the LED may further include a first metal layerforming an ohmic contact with the first conductive type semiconductorlayer through the exposed part of the first conductive typesemiconductor layer; and an upper insulating layer covering a part ofthe first metal layer, the side surfaces of the plurality of mesas, anda part of the second opening. The upper insulating layer is disposed toexpose the first metal layer through a third opening and partiallyexpose the reflective electrode layer through a fourth opening.

In some implementations, the LED may further include: a first padforming an ohmic contact with the first metal layer through the thirdopening; and a second pad forming an ohmic contact with the reflectiveelectrode layer through the fourth opening.

In another aspect, a method for manufacturing an LED is provided toinclude: forming a first conductive type semiconductor layer, an activelayer, and a second conductive type semiconductor layer over asubstrate; partially removing the second conductive type semiconductorlayer and the active layer, and forming a region which partially exposesthe first conductive type semiconductor layer; forming a defect blockinglayer including a masking region to cover at least a part of the topsurface of the second conductive semiconductor layer and an openingregion to partially expose the top surface of the second conductive typesemiconductor layer; forming a reflective electrode layer over thesecond conductive type semiconductor layer, the reflective electrodelayer forming form an ohmic contact with the second conductive typesemiconductor layer while covering at least a part of the defectblocking layer, and covering 90% or more of the surface of the secondconductive type semiconductor layer; and forming a first metal layerover the first conductive type semiconductor layer, the first metallayer forming an ohmic contact with the first conductive typesemiconductor layer. The defect blocking layer may include a firstregion and a second region surrounding the first region, and a ratio ofthe area of the opening region to the area of the masking region in thefirst region may be different from a ratio of the area of the openingregion to the area of the masking region in the second region.

In some implementations, the second region may be closer to the part atwhich the first metal layer forms an ohmic contact with the firstconductive type semiconductor layer, than the first region. In someimplementations, the ratio of the area of the opening region to the areaof the masking region in the first region may be greater than the ratioof the area of the opening region to the area of the masking region inthe second region.

In some implementations, the defect blocking layer may further include athird region surrounding the second region, the third region beingcloser to the part at which the first metal layer forms an ohmic contactwith the first conductive type semiconductor layer, than the secondregion. In some implementations, the ratio of the area of the openingregion to the area of the masking region in the second region may begreater than the ratio of the area of the opening region to the area ofthe masking region in the third region.

In some implementations, the defect blocking layer may further include aplurality of regions surrounding the second region, the first region,the second region, and the plurality of regions are arranged in theshape of a concentric polygon around the first region, and the ratio ofthe area of the opening region to the area of the masking region maygradually decrease along an outward direction from the center of thepolygonal shape.

In some implementations, the forming of the defect blocking layer mayinclude forming an insulating layer to cover at least a part of the topsurface of the second conductive type semiconductor layer; and formingthe opening region and the masking region in an embossed or engravedshape by patterning the insulating layer.

In some implementations, the forming of the insulating layer may includestacking dielectric layers having different refractive indexes.

In some implementations, the defect blocking layer may include aplurality of openings isolated from one another, and the plurality ofopenings may be filled with the reflective electrode layer.

In some implementations, the defect blocking layer may include aplurality of masks, and the plurality of masks may be covered by thereflective electrode layer.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows an image of a conventional light emitting diode (LED)including a reflection layer and a barrier layer are introduced.

FIG. 2 is a cross-sectional view showing a cracked portion of FIG. 1.

FIG. 3 is a cross-sectional view of an exemplary LED unit according toone implementation of the disclosed technology.

FIGS. 4 through 8 are cross-sectional views illustrating an exemplarymethod of manufacturing the LED unit of FIG. 3 according to oneimplementation of the disclosed technology. FIG. 4 shows an exemplaryLED structure. FIG. 5 shows an exemplary LED structure where portions ofan LED structure are removed by an exemplary etching process. FIG. 6shows an exemplary LED structure including a exemplary photoresistpattern. FIG. 7 shows an exemplary LED structure including an exemplaryreflection pattern. FIG. 8 shows an exemplary LED structure after thephotoresist pattern of FIG. 6 is removed.

FIGS. 9 through 18C are plan views and cross-sectional viewsillustrating a method of manufacturing an LED module including the LEDunit of FIG. 3 according to another implementation of the disclosedtechnology. FIG. 9 shows a plan view illustrating an exemplary LEDmodule. FIG. 10 shows a cross-sectional view taken along a line A-A′ inFIG. 9. FIG. 11 shows an exemplary LED module where a first insulatinglayer is disposed. FIGS. 12A and 12B show cross sectional views takenalong lines A1-A1′ and B1-B1′ in FIG. 11. FIG. 13 shows a plan viewillustrating an exemplary LED module where a conductive reflection layeris disposed. FIGS. 14A and 14B show cross sectional views taken alonglines A2-A2′ and B2-B2′ in FIG. 13. FIG. 15 shows an exemplary LEDmodule where a second insulating layer is disposed. FIGS. 16A to 16Cshow cross sectional views taken along lines A3-A3′, B3-B3′, and C-C′ inFIG. 15. FIG. 17 shows a plan view of an exemplary LED module where afirst pad a second pad are disposed. FIGS. 18A to 18C show crosssectional views taken along lines A4-A4′, B4-B4′, and C1-C1′ in FIG. 17.

FIG. 19 is a cross-sectional view of an LED package according to anotherimplementation of the disclosed technology.

FIGS. 20 through 29C are plan views and cross-sectional viewsillustrating a method of manufacturing an LED module including the LEDunit of FIG. 3 according to another implementation of the disclosedtechnology. FIG. 20 shows a plan view illustrating an exemplary LEDmodule. FIG. 21 shows a cross-sectional view taken along a line A-A′ inFIG. 20. FIG. 22 shows an exemplary LED module where a first insulatinglayer is disposed. FIGS. 23A and 23B show cross sectional views takenalong lines A1-A1′ and B1-B1′ in FIG. 22. FIG. 24 shows a plan viewillustrating an exemplary LED module where a conductive reflection layeris disposed. FIGS. 25A and 25B show cross sectional views taken alonglines A2-A2′ and B2-B2′ in FIG. 24. FIG. 26 shows an exemplary LEDmodule where a second insulating layer is disposed. FIGS. 27A to 27Cshow cross sectional views taken along lines A3-A3′, B3-B3′, and C-C′ inFIG. 26. FIG. 28 shows a plan view of an exemplary LED module where afirst pad a second pad are disposed. FIGS. 29A to 29C show crosssectional views taken along lines A4-A4′, B4-B4′, and C1-C1′ in FIG. 28.

FIG. 30 is a cross-sectional view of an LED package according to anotherimplementation of the disclosed technology.

FIGS. 31A through 38B are plan views and cross-sectional views fordescribing an LED and a method for manufacturing the same according toimplementations of the disclosed technology. FIGS. 31A and 31B show aplan view and a cross sectional view of an exemplary LED module. FIGS.32A and 32B show a plan view and a cross sectional view of an exemplaryLED module where a defect blocking layer is formed. FIGS. 33A to 33Cillustrate various shapes of a defect blocking layer. FIGS. 34A and 34Bshow a plan view and a cross sectional view of an exemplary LED modulewhere a reflective electrode layer is formed. FIGS. 35A and 35B show aplan view and a cross sectional view of an exemplary LED module where alower insulating layer is disposed. FIGS. 36A and 36B show a plan viewand a cross sectional view of an exemplary LED module where a firstmetal layer is disposed. FIGS. 37A and 37B show a plan view and a crosssectional view of an exemplary LED module where an upper insulatinglayer is disposed. FIGS. 38A and 38B show a plan view and a crosssectional view of an exemplary LED module where a first pad and a secondpad are disposed.

DETAILED DESCRIPTION

In the conventional flip chip-type LED, the reflection layer is formedto cover most of the p-type semiconductor layer, in order to improvereflection efficiency. However, when the reflection layer is in directcontact with the p-type semiconductor layer, potential existing in thep-type semiconductor layer may come in direct contact with thereflection layer. At this time, a leakage current may occur along thepotential which comes in direct contact with the reflection layer.Furthermore, when the leakage current is applied to a part vulnerable toexternal static electricity, the device may be destroyed by staticelectricity discharge.

Furthermore, the conventional flip chip-type LED has low currentspreading efficiency because the p-type semiconductor layer and thereflection layer are in direct contact with each other. Thus, currentcrowding may occur in a specific region. When a current crowding regionis formed in the semiconductor layer during an operation of the LED, thecurrent crowding region increases the probability that staticelectricity discharge will occur, because the current crowding region isvulnerable to static electricity.

In order to solve the problem of the conventional flip chip-type LED, acurrent blocking layer which is interposed between the p-typesemiconductor layer and the reflection layer has been suggested.However, when the current blocking layer is additionally introduced, aforward voltage may be increased. Furthermore, when the current blockinglayer is positioned without considering a current path, a leakagecurrent or static current discharge may not be efficiently prevented.

Hereinafter, exemplary implementations of the disclosed technology willbe described in detail. It should be understood, however, that thoseimplementations are provide as examples and there is no intent to limitthe disclosed technology to the implementations disclosed.

It will be understood that when a layer is referred to as being “on”another layer or substrate, it can be directly on the other layer orsubstrate or intervening layers may also be present. Terms that describespatial relationships, such as “on,” “upper,” “top surface,” “under,”“lower,” “bottom surface” and the like, may be used herein for ease ofdescription to describe one element or the relationship to anotherelement(s) or feature(s) as illustrated in the figures. It will beunderstood that such terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation(s) depicted in the figures.

Certain terms in this patent document such as first, second, etc. aremerely used to provide labels for various elements and the labels do notlimit the scope of the labeled elements. These labeling terms are onlyused to distinguish one element from another element, and the labelingterms do not specify an order or a temporal relationship among thelabeled elements.

In the drawings, the thicknesses of layers and regions may beexaggerated for clarity. Like reference numerals refer to like elementsthroughout.

FIG. 1 shows a conventional LED including a reflection layer and abarrier layer.

A reflection layer 20 is formed on a p-type semiconductor layer 10. Thereflection layer 20 is formed through an e-beam evaporation process. Thee-beam allows metal ions or atoms to have directionality and, a shape ofthe reflection layer 20 may be determined by an entrance angle of themetal ions or atoms. A side portion of the reflection layer 20 tend tonot have a substantially vertical profile with respect to the p-typesemiconductor layer 10 and rather forms a predetermined angle withrespect to a surface of the p-type semiconductor layer 10. For example,when the reflection layer 20 includes silver (Ag), it is difficult forthe reflection layer 20 to have a vertical profile due to inherentdiffusivity. Accordingly, it is general to obtain a nearly verticalprofile by controlling an angle of a substrate with respect to adirection in which metal ions or atoms proceed from a target.

A barrier layer 30 is introduced on the reflection layer 20. In FIG. 1,the barrier layer 30 has a structure in which two kinds of metal layersare alternately formed. The barrier layer 30 is provided to preventdiffusion of metal atoms of the reflection layer 20. For example, thebarrier layer 30 is formed by alternately stacking a Ti layer and a TiWlayer. Alternatively, the barrier layer 30 may be obtained byrepetitively forming a single kind of metal layer instead of two kindsof metal layers.

The various conditions including diffusion coefficients and thermalexpansion coefficients of a metal of the barrier layer 30 that isstacked during the formation of the barrier layer 30 cause the structureof the barrier layer 30 to be spontaneously destroyed or crack. Thisproblem becomes worse as the underlying reflection layer 20 has aprofile closer to a vertical profile.

In FIG. 1, on the reflection layer 20 including Ag, a first barrierlayer 31 and a second barrier layer 32 are formed to include Ag andtitanium tungsten (TiW), respectively. A side surface of the reflectionlayer 20 forms an angle at a surface of a p-type semiconductor layer 10exceeding about 45°. The barrier layer 30 is deposited on a profilehaving a high inclination. The deposition process is generally performedusing a sputtering process.

The first barrier layer 31 and the second barrier layer 32 arealternately stacked along the inclined profile. However, as the numberof times the first and second barrier layers 31 and 32 are stackedincreases and the thickness of the barrier layer 30 increases, thebarrier layer 30 is likely to crack in the inclined side surfaces of thereflection layer 20. The cracks occur more frequently if the barrierlayer 32 includes two different kinds of metals that are alternatelystacked and as the inclination angle of a side profile of the reflectionlayer 20 increases. FIG. 1 shows a cracked portion 40.

FIG. 2 is a cross-sectional view showing the cracked portion of FIG. 1.

Referring to FIG. 2, as the number of the first barrier layer 31 and thesecond barrier layer 32 that are alternately formed on side surfaces ofthe reflection layer 20 increases, the thicknesses of the first andsecond barrier layers 31 and 32 formed on the side surfaces of thereflection layer 20 decreases, and a phenomenon occurs that the firstand second barrier layers 31 and 32 are not any longer deposited on theside surfaces of the reflection layer 20. Accordingly, a portion isformed along the barrier layer 30, in which the first barrier layer 31or the second barrier layer becomes discontinuous. Thus, a crack occursin the barrier layer 30. The crack occurred in the barrier layer 30cause metal atoms of the reflection layer 20 to diffuse. Accordingly, asheterogeneous metals are introduced in a subsequent process includingforming an electrode, electrical properties are degraded.

The causes why the crack portion is formed as shown in FIGS. 1 and 2 maybe analyzed in various approaches.

For example, the barrier layer 30 may be formed near a top surface ofthe reflection layer 20 to have a relatively great thickness, while thebarrier layer 30 may be formed on side surfaces of the reflection layer20 to have a relatively small thickness. When this phenomenon continuesor worsens, a discontinuous portion is formed in the first barrier layer31 or the second barrier layer 32.

Furthermore, cracks may occur in a specific barrier layer due to adifference in coefficient of thermal expansion between two kinds ofmetal materials during the deposition of the two kinds of metalmaterials. The cracks in the first barrier layer 31 or the secondbarrier layer 32 are not cured during a subsequent deposition process,and the cracks occur more frequently as a deposition process proceeds.It can be seen from FIG. 1 that a crack or discontinuity is more serioustoward an upper portion of the cracked portion 40.

Cracks formed in a barrier layer adversely affect characteristics of anLED. For example, metal atoms may diffuse from a reflection layer,thereby degrading electrical properties. Also, since an LED has astacked structure of multiple layers, cracks in the barrier layer becomeworse depending on the environment in which an LED is used. The cracksin the barrier layer fatally affect the reliability of the LED.

Furthermore, when a surface-mount LED module is manufactured using theabove described LED with cracks, local crowding of current supplied froma pad occurs due to the cracks in the barrier layer. For instance, evenif a high voltage or current is applied to increase luminance, since thecurrent crowds in a p-GaN layer, luminance is reduced.

FIG. 3 is a cross-sectional view of an exemplary light emitting diode(LED) unit provided according to one implementation of the disclosedtechnology.

Referring to FIG. 3, a first semiconductor layer 110, an active layer120, a second semiconductor layer 130, and a reflection pattern 140 areformed on a substrate 100.

The substrate 100 may be formed of or include any material capable ofinducing the first semiconductor layer 110 to be grown. Accordingly, thesubstrate 100 may include sapphire (Al2O3), silicon carbide (SiC),gallium nitride (GaN), indium gallium nitride (InGaN), aluminum galliumnitride (AlGaN), aluminum nitride (AlN), gallium oxide (Ga2O3), orsilicon. In one implementation, the substrate 100 may be or include asapphire substrate.

Also, the substrate 100 may be or include a substrate on which surfacetreatment is not performed. The substrate 100 may be patterned. Also, asurface of the substrate 100 may have a moth-eye structure. For example,the substrate 100 may have a protrusion protruding in a roughlyhemispherical shape, and pointed structures may be densely disposed onthe protrusion.

The first semiconductor layer 110 is formed on the substrate 100. As oneexample, the first semiconductor layer 110 has an n conductivity type.

The active layer 120 may be formed on the first semiconductor layer 110.The active layer 120 may have a single quantum well (SQW) structure inwhich a well layer and a barrier layer are stacked, or a multi-quantumwell (MQW) structure in which well layers and barrier layers arealternately stacked.

The second semiconductor layer 130 is formed on the active layer 120. Asone example, the second semiconductor layer 130 has a p conductivitytype.

The first semiconductor layer 110, the active layer 120, and the secondsemiconductor layer 130 may include Si, GaN, AlN, InGaN, or AlInGaN.When the first semiconductor layer 110 includes GaN, the active layer120 and the second semiconductor layer 130 include GaN. However, sincethe second semiconductor layer 130 has a complementary conductivity typeto the first semiconductor layer 110, a different dopant from that ofthe first semiconductor layer 110 is introduced into the secondsemiconductor layer 130. For example, when a dopant serving as a donoris introduced into the first semiconductor layer 110, a dopant servingas an acceptor is introduced into the second semiconductor layer 130.Also, the active layer 120 may include a material on which bandgapengineering is performed to form a barrier layer and a well layer.

The reflection pattern 140 is formed on the second semiconductor layer130.

The reflection pattern 140 includes a reflective metal layer 142 and aconductive barrier layer 144. In some implementations, an ohmic contactlayer (not shown) may be formed under the reflective metal layer 142,and a stress relaxation layer (not shown) may be formed between thereflective metal layer 142 and the conductive barrier layer 144.

An ohmic contact layer may be formed of or include any material capableof enabling ohmic contact between the reflective metal layer 142 and thesecond semiconductor layer 130. Accordingly, the ohmic contact layer mayinclude a metal including nickel (Ni) or platinum (Pt) or include aconductive oxide, such as indium tin oxide (ITO) or zinc oxide (ZnO). Insome implementations, the ohmic contact layer may be omitted.

If the ohmic contact layer is provided, the reflective metal layer 142is formed on the ohmic contact layer. The reflective metal layer 142reflects light generated in the active layer 120. Accordingly, thereflective metal layer 142 is formed with a material having conductivityand high optical reflectance. The reflective metal layer 142 includessilver (Ag), a Ag alloy, aluminum (Al), or an Al alloy.

In some implementations, a stress relaxation layer may be formed on thereflective metal layer 142. The stress relaxation layer may have acoefficient of thermal expansion equal to or higher than that of theconductive barrier layer 144, and equal to or lower than that of thereflective metal layer 142. Thus, stress caused due to a difference incoefficient of thermal expansion between the reflective metal layer 142and the conductive barrier layer 144 may be reduced. Accordingly, amaterial used for the stress relaxation layer may be selected dependingon materials used for the reflective metal layer 142 and the conductivebarrier layer 144.

As discussed above, the ohmic contact layer or the stress relaxationlayer may be omitted according to various implementations of thedisclosed technology.

An angle α that the reflective metal layer 142 forms with respect to asurface of the underlying second semiconductor layer 130 may range fromabout 5° to about 45°. When an angle α formed by a side surface of thereflective metal layer 142 is less than about 5°, it is difficult tosecure a sufficient thickness of the reflective metal layer 142. Whenthe angle α formed by the side surface of the reflective metal layer 142is more than about 45°, cracks occur in a side profile of the conductivebarrier layer 144 formed on the reflective metal layer 142. When anohmic contact layer is introduced, an inclination angle that the ohmiccontact layer forms with respect to the side surface of the reflectivemetal layer 142 may have the same range as that between the reflectivemetal layer 142 and the second semiconductor layer 130.

The conductive barrier layer 144 is formed on the reflective metal layer142 or the stress relaxation layer 143. For example, when the stressrelaxation layer 143 is omitted, the conductive barrier layer 144 isformed on the reflective metal layer 142, and when the stress relaxationlayer 143 is formed, the conductive barrier layer 144 is formed on thestress relaxation layer 143. The conductive barrier layer 144 is formedto surround at least the side surface of the reflective metal layer 142and surround top and side surfaces of the stress relaxation layer 143.Accordingly, diffusion of metal atoms or ions of the reflective metallayer 142 is prevented. Also, stress caused due to a difference incoefficient of thermal expansion between the conductive barrier layer144 and the reflective metal layer 142 may be absorbed in the stressrelaxation layer 143. In particular, the conductive barrier layer 144may be formed to have a different thickness depending on a surface stateof the underlying layer that may be the reflective metal layer 142 orstress relaxation layer 143. For example, assuming that the thickness ofthe conductive barrier layer 144 formed on a top surface of thereflective metal layer 142 or the stress relaxation layer 143 is t1, thethickness of the conductive barrier layer 144 formed on the side surfaceof the reflective metal layer 142 is t2, and the thickness of theconductive barrier layer 144 formed on the surface of the secondsemiconductor layer 130 is t3, a relationship of t1>t3>t2 is set.

In addition, the conductive barrier layer 144 is formed to completelyshield or cover the uppermost layer of the reflection pattern 140, forexample, the reflective metal layer 142 or the stress relaxation layer143, and extend to the surface of the second semiconductor layer 130.

In addition, when the reflective metal layer 142 includes Al or an Alalloy, and the conductive barrier layer 144 includes W, TiW, or Mo, thestress relaxation layer 143 may be a single layer formed of or includingAg, Cu, Ni, Pt, Ti, Rh, Pd, or Cr, or a combination formed of orincluding Cu, Ni, Pt, Ti, Rh, Pd or Au. Also, when the reflective metallayer 142 includes Al or an Al alloy, and the conductive barrier layer144 includes Cr, Pt, Rh, Pd, or Ni, the stress relaxation layer 143 maybe a single layer formed of or including Ag or Cu, or a combinationformed of or including Ni, Au, Cu, or Ag.

Furthermore, when the reflective metal layer 142 includes Ag or a Agalloy, and the conductive barrier layer 144 includes W, TiW, or Mo, thestress relaxation layer 143 may be a single layer formed of or includingCu, Ni, Pt, Ti, Rh, Pd, or Cr, or a combination formed of or includingCu, Ni, Pt, Ti, Rh, Pd, Cr, or Au. Also, when the reflective metal layer142 includes Ag or a Ag alloy, and the conductive barrier layer 144includes Cr or Ni, the stress relaxation layer 143 may be a single layerformed of or including Cu, Cr, Rh, Pd, TiW, or Ti, or a combinationformed of or including Ni, Au, or Cu.

In addition, the conductive barrier layer 144 extends over the surfaceof the second semiconductor layer 130.

FIGS. 4 through 8 are cross-sectional views illustrating an exemplarymethod of manufacturing the LED unit of FIG. 3 according to oneimplementation of the disclosed technology.

Referring to FIG. 4, a first semiconductor layer 110, an active layer120, and a second semiconductor layer 130 are sequentially formed on asubstrate 100.

The substrate 100 may include sapphire (Al2O3), silicon carbide (SiC),gallium nitride (GaN), indium gallium nitride (InGaN), aluminum galliumnitride (AlGaN), aluminum nitride (AlN), gallium oxide (Ga2O3), orsilicon. In one implementation, the substrate 100 may be a sapphiresubstrate. Also, the substrate 100 may be patterned or have a surfacewith a moth-eye structure.

The first semiconductor layer 110 is provided on the substrate 100. Asone example, the first semiconductor layer 110 has an n conductivitytype.

In addition, the active layer 120 formed on the first semiconductorlayer 110 may have an SQW structure in which a well layer and a barrierlayer are stacked, or an MQW structure in which well layers and barrierlayers are alternately stacked.

The second semiconductor layer 130 is provided on the active layer 120.As one example, the second semiconductor layer 130 has a p conductivitytype.

Materials and structures of the first semiconductor layer 110, theactive layer 120, and the second semiconductor layer 130 are the same asthose described with reference to FIG. 3, and thus detailed descriptionsare omitted.

In addition, the first semiconductor layer 110, the active layer 120,and the second semiconductor layer 130 are formed using an epitaxialgrowth process. Accordingly, the first semiconductor layer 110, theactive layer 120, and the second semiconductor layer 130 may be formedusing an MOCVD process.

Referring to FIG. 5, portions of the active layer 120 and the secondsemiconductor layer 130 are removed using an etching process. Thus,portions of the first semiconductor layer 110 are exposed. In oneimplementation, after the etching process, selective portions of a topsurface of the first semiconductor layer 110 are exposed, and sidesurfaces of the active layer 120 and the second semiconductor layer 130are exposed. Through the etching process of removing portions of theactive layer 120 and the second semiconductor layer 130, a trench or ahole may be formed. A mesa region 150 is formed in FIG. 5 by etchingfrom the surface of the second semiconductor layer 130 to the surface ofthe first semiconductor layer 110. The mesa region 150 may be or includea stripe type having a trench shape or a hole type.

When the mesa region 150 has the stripe type, the mesa region 150 mayhave a vertical profile or inclined profile with respect to the surfaceof the first semiconductor layer 110. In one implementation, the mesaregion 150 has a profile inclined at an angle of about 20° to about 70°with respect to the surface of the first semiconductor layer 110. Whenthe mesa region 150 has a hole type having a roughly circular shape, themesa region 150 may have a vertical profile or inclined profile withrespect to the surface of the first semiconductor layer 110. In oneimplementation, the mesa region 150 has a profile inclined at an angleof about 20° to about 70° with respect to the surface of the firstsemiconductor layer 110. If the mesa region 150 is inclined at an angleof less than 20°, the mesa region 150 has a greatly increased width inthe upper portion of the mesa region 150. In this case, since thestructure of the mesa region 150 allows the generated light to emit,convergence of the generated light is degraded. If the mesa region 150is inclined at an angle of more than 70°, the mesa region 150 has anearly vertical profile. In this case, the sidewalls of layers do noteffectively reflect the generated light as compared to the inclinedsidewalls.

Referring to FIG. 6, a photoresist pattern 160 is formed on the exposedportion of the first semiconductor layer 110, which form a bottomsurface of the mesa region. The photoresist pattern 160 may have avertical profile with respect to the surface of the first semiconductorlayer 110. In some implementations, the photoresist pattern 160 may beformed to have an overhang structure having a bottom surface with asmaller width than a top surface thereof. In one implementation, thephotoresist pattern 160 may have a negative type. Accordingly, exposedportions are cross-linked. To form the overhang structure, thephotoresist pattern 160 is exposed while being inclined at apredetermined angle. In the case of the overhang structure, a distancebetween bottom surfaces of the photoresist patterns 160 may be greaterthan or equal to a distance between top surfaces of the photoresistpatterns 160. In one implementation, the difference between thedistances on the bottom and top surfaces of the photoresist patterns 160may be at least about 1 μm.

Furthermore, the photoresist pattern 160 may be provided to cover aportion of the surface of the second semiconductor layer 130.Accordingly, the portion of the top surface of the second semiconductorlayer 130 may remain shielded or covered by the photoresist pattern 160.

Next, a reflection pattern 140 is formed to include a reflective metallayer 142 and a conductive barrier layer 144 that are sequentiallystacked on the second semiconductor layer 130. As discussed above, insome implementations, an ohmic contact layer 141 may be formed under thereflective metal layer 142, and a stress relaxation layer 143 may beformed between the reflective metal layer 142 and the conductive barrierlayer 144. In FIG. 7, as one example, the reflection pattern 140 isshown to include the ohmic contact layer 141, the reflective metal layer142, the stress relaxation layer 143 and the conductive barrier layer144.

The reflective metal layer 142 includes Al, an Al alloy, Ag, or a Agalloy. The reflective metal layer 142 may be formed using a metaldeposition process. In one implementation, the reflective metal layer142 is formed using an electronic beam (e-beam) evaporation processcapable of moving most metal atoms or ions onto the surface of thesecond semiconductor layer 130 in a vertical direction. Thus, the metalatoms or ions which have anisotropic etching characteristics may enter aspace between the photoresist patterns 160 to form the reflective metallayer 142.

In some implementations, the reflective metal layer 142 has a thicknessof about 100 nm to about 1 μm. When the reflective metal layer 142 has athickness of less than about 100 nm, light generated in the active layer120 is not smoothly reflected. Also, when the reflective metal layer 142has a thickness of more than about 1 μm, process loss may occur due toan excessive process time.

In some implementations, if the ohmic contact layer 141 is provided, theohmic contact layer 141 may be formed before forming the reflectivemetal layer 142. The ohmic contact layer 141 may include Ni, Pt, ITO, orZnO. In one implementation, the ohmic contact layer 141 may be formed tohave a thickness of about 0.1 nm to about 20 nm. When the ohmic contactlayer 141 has a thickness of less than about 0.1 nm, sufficient ohmiccharacteristics cannot be ensured due to a very small thickness. Whenthe ohmic contact layer 141 has a thickness of more than about 20 nm,the amount of light transmitted is reduced, and the amount of lightreflected by the reflective metal layer 142 is reduced.

In some implementations, the stress relaxation layer 143 is formed onthe reflective metal layer 142.

In this case, the stress relaxation layer 143 may be formed using ametal deposition process. In one implementation, the stress relaxationlayer 143 may be formed using an e-beam evaporation method having highdirectionality during a deposition process. That is, metal atoms or ionsevaporated by e-beams may have directionality and anisotropy in a spacebetween the photoresist patterns 160. In one implementation, the stressrelaxation layer 143 may be formed of or include a metal layer. Also,the stress relaxation layer 143 may have a thermal expansion coefficientthat is lower than the reflective metal layer 142 and higher than theconductive barrier layer 144 of FIG. 3. Accordingly, a material of thestress relaxation layer 143 may be selected depending on materials ofthe reflective metal layer 142 and the conductive barrier layer 144.

When the reflective metal layer 142 and the stress relaxation layer 143are formed using an e-beam evaporation method, a side surface of thereflective metal layer 142 and a side surface of the stress relaxationlayer 143 are exposed. In some implementations, the reflective metallayer 142 and the stress relaxation layer 143 corresponding to an openupper region of the photoresist pattern 160 are formed using ananisotropic deposition process.

In an e-beam evaporation process, upper layers formed by the e-beamevaporation process are formed along a profile of a side surface of thestress relaxation layer 143 such that the upper layers are provided tocover or shield underlying layers. In one implementation, a side surfaceof a structure including the stress relaxation layer 143 or thereflective metal layer 142, which is formed using the e-beam evaporationprocess, is inclined at an angle α of about 5° to about 45°.

FIG. 7 illustrates a state in which a metal is not formed on thephotoresist pattern 160 during the formation of the reflective metallayer 142 and the stress relaxation layer 143.

Next, a conductive barrier layer 144 is formed through the opened regionof the photoresist pattern 160.

The conductive barrier layer 144 includes W, TiW, Mo, Cr, Ni, Pt, Rh,Pd, or Ti. A material of the conductive barrier layer 144 may varydepending on materials of the reflective metal layer 142 or the stressrelaxation layer 143.

The conductive barrier layer 144 is formed on the stress relaxationlayer 143 and shields side surfaces of the reflective metal layer 142 orthe stress relaxation layer 143. Accordingly, a metal of the reflectivemetal layer 142 is prevented from diffusing into the secondsemiconductor layer 130 through lateral diffusion. The formation of theconductive barrier layer 144 is performed using a metal depositionprocess. In one implementation, the conductive barrier layer 144 isformed using an isotropic etching process. This is because theconductive barrier layer 144 is configured to surround the side surfacesof the stress relaxation layer 143 and the reflective metal layer 142.For example, the conductive barrier layer 144 may be formed using asputtering process.

In one implementation, the conductive barrier layer 144 may be a singlelayer with a thickness of about 100 nm or more and including a specificmetal. In another implementation, the conductive barrier layer 144 mayinclude at least two metal materials that are alternately stacked, eachmetal material forming a layer of the conductive barrier layer 144 tohave a thickness of about 20 nm or more. For example, the conductivebarrier layer 144 may be formed by alternately depositing a TiW layerhaving a thickness of about 50 nm and a Ni layer or Ti layer having athickness of about 50 nm.

The conductive barrier layer 144 has a different thickness according tovarious conditions of the underlying layer including a state or gradientof an underlying layer. The conductive barrier layer 144 is formed toextend to an upper portion of the second semiconductor layer 130. Sincea gradient a of a side surface of the underlying layer has an angle ofabout 45° or less, occurrence of cracks that is caused by the sharpgradient is prevented in the conductive barrier layer 144.

In some implementations, a Ni/Au/Ti layer may be additionally formed onthe conductive barrier layer 144 to enable stable contact of theconductive barrier layer 144 with a material during a subsequentprocess.

As described above, a material of the stress relaxation layer 143 may beselected according to the materials of the reflective metal layer 142and the conductive barrier layer 144. This is because a coefficient ofthermal expansion of the stress relaxation layer 143 is higher than thatof the conductive barrier layer 144 and lower than that of thereflective metal layer 142. Accordingly, when the reflective metal layer142 includes Al or an Al alloy, and the conductive barrier layer 144includes W, TiW, or Mo, the stress relaxation layer 143 may be a singlelayer formed of or including Ag, Cu, Ni, Pt, Ti, Rh, Pd, or Cr, or acombination formed of or including Cu, Ni, Pt, Ti, Rh, Pd or Au. Also,when the reflective metal layer 142 includes Al or an Al alloy, and theconductive barrier layer 144 includes Ti, Cr, Pt, Rh, Pd, or Ni, thestress relaxation layer 143 may be a single layer formed of or includingAg or Cu, or a combination formed of or including Ni, Au, Cu, or Ag.Furthermore, when the reflective metal layer 142 includes Ag or a Agalloy, and the conductive barrier layer 144 includes W, TiW, or Mo, thestress relaxation layer 143 may be a single layer formed of or includingCu, Ni, Pt, Ti, Rh, Pd, or Cr, or a combination formed of or includingCu, Ni, Pt, Ti, Rh, Pd, Cr, or Au. Also, when the reflective metal layer142 includes Ag or a Ag alloy, and the conductive barrier layer 144includes Pt or Ni, the stress relaxation layer 143 may be a single layerformed of or including Cu, Cr, Rh, Pd, TiW, or Ti, or a combinationformed of or including Ni, Au, or Cu.

Referring to FIG. 8, the photoresist pattern 160 is removed.Accordingly, the second semiconductor layer 130 and the reflectionpattern 140 are exposed. For example, edge portions of the secondsemiconductor layer 130 and the reflection pattern 140 disposed betweenthe edge portions of the second semiconductor layer 130 are exposed.Also, the mesa region 150 is exposed by removing the photoresist pattern160. This is the same as described with reference to FIG. 3.

Due to the above-described processes, the reflection pattern 140 isformed on the second semiconductor layer 130. The reflection pattern 140includes a reflective metal layer 142, a stress relaxation layer 143,and a conductive barrier layer 144. The stress relaxation layer 143 hasa lower coefficient of thermal expansion than the reflective metal layer142 and a higher coefficient of thermal expansion than the conductivebarrier layer 144. Accordingly, stress caused due to a difference incoefficient of thermal expansion between the reflective metal layer 142and the conductive barrier layer 144 is absorbed in the stressrelaxation layer 143. As discussed above, the stress relaxation layer143 can be omitted in some implementations.

In addition, the conductive barrier layer 144, which is formed on thereflective metal layer 142 or the stress relaxation layer 143, has adifferent thickness according to various properties of the underlyinglayer including the shape and type of the underlying layer. For example,a thickness t1 of the conductive barrier layer 144 formed on the surfaceof the reflective metal layer 142 or the stress relaxation layer 143 isgreater than a thickness t3 of the conductive barrier layer 144 formedon the surface of the second semiconductor layer 130. Also, thethickness t3 formed on the second semiconductor layer 130 is greaterthan a thickness t2 of the conductive barrier layer 144 formed on sidesurfaces of the reflective metal layer 142 or the stress relaxationlayer 143.

The above difference in thickness is obtained by performing an isotropicdeposition process after forming a photoresist pattern having anoverhang structure. That is, deposition is performed to the highestextent on a top surface of the reflective metal layer 142 or stressrelaxation layer 144, which is exposed by the photoresist pattern, anddeposition may be performed to a relatively high extent on a surface ofthe second semiconductor layer 130 because the second semiconductorlayer 130 has a planar structure. In contrast, since a side surface ofthe reflective metal layer 142 or the stress relaxation layer 143 has apredetermined inclination and a metal to be deposited should be adheredto sidewalls of the reflective metal layer 142 or the stress relaxationlayer 143, the deposition is performed to a relatively low extent on theside surface of the reflective metal layer 142 or the stress relaxationlayer 143.

Furthermore, the side surface of the reflective metal layer 142 or thestress relaxation layer 143 is inclined at an angle α of about 5° toabout 45°. A required inclination angle may be formed by controlling anangle of a substrate during an e-beam evaporation process. For example,by orienting the substrate at a predetermined angle with respect to animaginary direction in which metal ions or particles are predicted toproceed, the inclination angle α of the side surface of the reflectivemetal layer 142 or the stress relaxation layer 143 may be controlled. Bysetting the inclination angle α of the side surface, occurrence ofcracks can be prevented in a conductive barrier layer 144 during asubsequent process.

FIGS. 9 through 18C are plan views and cross-sectional viewsillustrating an exemplary method of manufacturing an LED moduleaccording to another implementation of the disclosed technology.

FIG. 9 shows a plan view illustrating an exemplary method ofmanufacturing an LED module and FIG. 10 shows a cross-sectional viewtaken along the line A-A′ of FIG. 9.

As explained above, a first semiconductor layer 110, an active layer120, and a second semiconductor layer 130 are sequentially stacked on asubstrate 100, and a mesa region 150 is formed using an etching process.A portion of a surface of the first semiconductor layer 110 is exposedthrough the mesa region 150. Also, a reflection pattern 140 is formed onthe second semiconductor layer 130.

In the drawings of the present implementation, the reflection pattern140 is exaggerated for brevity. In one implementation, the reflectionpattern 140 may be formed in the same manner as described with regard toFIGS. 4 through 8. In another implementation, the reflection pattern 140may be formed using other different techniques.

In some implementations, the substrate 100 may be a substrate on whichsurface treatment is not performed, or a patterned substrate. Also, asurface of the substrate 100 may have a moth-eye structure. For example,pointed structures 100 a may be densely disposed on the surface of thesubstrate 100. Alternatively, the substrate 100 may have a protrusionprotruding in a roughly hemispherical shape, and pointed structures maybe densely disposed on the protrusion.

Referring to FIGS. 11 and 12A to 12B, a first insulating layer 200 isformed on the resultant structure of FIG. 9. The first insulating layer200 may be formed of or include a transparent nonconductor. In oneimplementation, silicon oxide may be used as the first insulating layer200. The first insulating layer 200 is patterned using a photoresistprocess. By patterning the first insulating layer 200, the firstsemiconductor layer 110 formed in the mesa region 150 is exposed, andselective portions of the reflection pattern 140 are exposed. A firstpad region 205 is defined to include the exposed selective portions ofthe reflection pattern 140 and the patterned first insulating layer 200formed on the reflection pattern 140.

FIG. 11 shows a plan view illustrating an exemplary method ofmanufacturing an LED module and FIGS. 12A and 12B show cross-sectionalviews taken along the line A1-A1′ and the line B1-B1′ of FIG. 11.

Referring to the cross-sectional view taken along the direction A1-A1′,the first insulating layer 200 has a patterned shape on the reflectionpattern 140 to expose selective portions of the reflection pattern 140.Also, the first insulating layer 200 is not formed in in the mesa region150 to expose the first semiconductor layer 110. In one implementation,the reflection pattern 140 exposed by the first insulating layer 200 inthe first pad region 205 may be provided in the form of a hole 200 a asshown in FIG. 12A. However, other implementations are also possible suchthat the reflection pattern 140 exposed by the first insulating layer200 in the first pad region 205 may be or include a stripe form.

Referring to the cross-sectional view in FIG. 12B taken along thedirection B1-B1′, the first insulating layer 200 completely shields orcovers the reflection pattern 140. The first semiconductor layer 110 isexposed in the mesa region 150.

Referring to FIGS. 13 and 14A to 14B, a conductive reflection layer 210is formed.

Referring to FIG. 13, the conductive reflection layer 210 is coated onthe entire surface of the resultant structure of FIG. 11 except anopening 210 a. The first pad region 205 is exposed within the opening210 a. Also, the conductive reflection layer 210 is formed in the mesaregion 150 and electrically connected to the first semiconductor layer110.

FIG. 13 shows a plan view illustrating an exemplary method ofmanufacturing an LED module and FIGS. 14A and 14B show cross-sectionalviews taken along the line A2-A2′ and the line B2-B2′ of FIG. 13.

Referring to the cross-sectional view in FIG. 14A taken along the lineA2-A2′, the conductive reflection layer 210 is formed on the firstinsulating layer 200 and the exposed first semiconductor layer 110.

Accordingly, the conductive reflection layer 210 is coated on the entiresurface except the first pad region 205. Also, the conductive reflectionlayer 210 is formed on the first semiconductor layer 110 exposed in themesa region 150 and electrically connected to the first semiconductorlayer 110.

The conductive reflection layer 210 is formed of or includes aconductive material. The conductive reflection layer 210 may include Al.Accordingly, the first semiconductor layer 110 and the conductivereflection layer 210 are electrically connected, and the reflectionpattern 140 is electrically insulated from the conductive reflectionlayer 210 by the first insulating layer 200.

In addition, a reflection barrier layer (not shown) may be formed on theconductive reflection layer 210. The reflection barrier layer preventsdiffusion of a metal of the conductive reflection layer 210. In oneimplementation, the reflection barrier layer may be a single layerformed of or including Ni, Cr, or Au, or a combination thereof. Inanother implementation, the reflection barrier layer is a combined layerformed of or including Ti/Al/Ti/Ni/Au. Also, an adhesive layer (notshown) may be further provided under the conductive reflection layer210. The adhesive layer may include Ti, Cr, or Ni.

The conductive reflection layer 210 may be formed by stacking theconductive reflection layer 210 and patterning the conductive reflectionlayer 210 using an etching process. Alternatively, the conductivereflection layer 210 may be formed using a lift-off process. That is,photoresist is coated on the first pad region 205 in which selectiveportions of the reflection pattern 140 are exposed, and the conductivereflection layer 210 is formed using a deposition process. Then, byremoving the photoresist from the first pad region 205, the conductivereflection layer 210 is formed to expose the first pad region 205.

Referring to FIGS. 15 and 16A to 16C, a second insulating layer 220 isformed on the resultant structure of FIG. 13.

Referring to a plan view of FIG. 15, the second insulating layer 220includes first holes 220 a and second holes 220 b. The first holes 220 aare formed in the first pad region 205, and a second pad region 225 isdefined by the second holes 220 b to be under the first pad region 225.Selective portions of the conductive reflection layer 210 are exposed bythe second holes 220 b formed in the second pad region 225. When areflection barrier layer is formed on the conductive reflection layer210, selective portions of the reflection barrier layer may be exposedby the second holes 220 b formed in the second pad region 225.

In FIG. 15, the number of first holes 220 a may be equal to or greaterthan the number of second holes 220 b. This facilitates diffusion ofcurrent through the reflection pattern 140 exposed by the first holes220 a. When the second semiconductor layer 130 is or includes a p-typesemiconductor layer, current division into the p-type semiconductorlayer becomes a problem in applying current. Accordingly, by controllingthe number of first holes 220 a to be equal to or greater than thenumber of second holes 220 b, current can be smoothly divided into thesecond semiconductor layer 130.

This will be clearly described with reference to a cross-sectional viewof FIGS. 16A to 16C.

FIG. 15 shows a plan view illustrating an exemplary method ofmanufacturing an LED module and FIGS. 16A to 16C show cross-sectionalviews taken along lines A3-A3′, B3-B3′, and C-C′ of FIG. 15.

The line A3-A3′ of FIG. 16A crosses the first pad region 205, and thesecond insulating layer 220 is formed on the conductive reflection layer210 in the cross-sectional view taken along the line A3-A3′. When areflection barrier layer is formed on the conductive reflection layer210, the second insulating layer 220 is formed on the reflection barrierlayer. The second insulating layer 220 has the first holes 220 a in thefirst pad region 205, and is also formed on the mesa region 150. In someimplementations, the second insulating layer 220 may be formed on thefirst insulating layer 200 formed on the first pad region 205. In otherimplementations, the second insulating layer 220 may be not formed onthe first insulating layer 200 disposed in the first pad region 205.

Also, the line B3-B3′ of FIG. 16B crosses the second pad region 225, andthe second insulating layer 220 is formed on the conductive reflectionlayer 210 disposed on the mesa region 150 in the cross-sectional viewtaken along the line B3-B3′. In addition, the second insulating layer220 is formed to expose selective portions of the conductive reflectionlayer 210 formed on the reflection pattern 140 except the mesa region150. That is, the second insulating layer 220 is provided in a patternedshape on the conductive reflection layer 210 disposed on the reflectionpattern 140. Accordingly, the selective portions of the conductivereflection layer 210 are exposed to define the second pad region 225.The second pad region 225 includes the exposed selected portion of theconductive reflection layer 210 and the patterned second insulatinglayer 220 formed on the conductive reflection layer 210. In someimplementations, the portion of the conductive reflection layer 210 maybe also exposed on the mesa region 150. Furthermore, the secondinsulating layer 220 in the second pad region 225 may expose theconductive reflection layer 210 such that the exposed conductivereflection layer 210 forms in the shape of the second holes 220 b or ina stripe form.

The line C-C′ of FIG. 16C crosses the first pad region 205 and thesecond pad region 225, and the second insulating layer 220 is formed onthe conductive reflection layer 210 in the cross-sectional view takenalong the line C-C′. The second insulating layer 220 exposes selectiveportions of the underlying reflection pattern 140 in the first padregion 205, and shields or covers the conductive reflection layer 210between the first and second pad regions 205 and 225. Also, the secondinsulating layer 220 is provided in a patterned shape in the second padregion 225 to expose the underlying conductive reflection layer 210.

The second insulating layer 220 may be formed of or include anyinsulating material. In some implementations, an oxide-based insulatingmaterial, a nitride-based insulating material, a polymer (e.g.,polyimide, Teflon, or parylene) may be used for the second insulatinglayer 220.

Referring to FIGS. 17 and 18A to 18C, a first pad 230 and a second pad240 are formed on the resultant structure of FIG. 15. The first pad 230is electrically connected to the exposed reflection pattern 140 of thefirst pad region 205 in FIGS. 15 and 16A to 16C. Accordingly, the firstpad 230 and the second semiconductor layer 130 are electricallyconnected. The second semiconductor layer 130 is electrically connectedto an external power source or power supply line through the first pad230.

The second pad 240 is electrically connected to the exposed conductivereflection layer 140 of the second pad region 225 in FIGS. 15 and 16A to16C. Accordingly, the second pad 240 and the first semiconductor layer110 are electrically connected. The first semiconductor layer 110 iselectrically connected to an external power source or power supply linethrough the second pad 240.

In some implementations, an area of the first pad 230 electricallyconnected to the second semiconductor layer 130 is controlled to begreater than an area of the second pad 240 electrically connected to thefirst semiconductor layer 110. If the second semiconductor layer 130 isa p-type semiconductor layer, heat emission through the p-typesemiconductor layer may be a problem. By increasing a contact areabetween the second pad 240 and a printed circuit board (PCB) to begreater than the area of the first pad 230, the problem regarding heatemission can be solved.

The first pad 230 and the second pad 240 may have a double layeredstructure including a layer including Ti, Cr, or Ni and a layerincluding Al, Cu, Ag, or Au. Also, the first pad 230 and the second pad240 may be formed by patterning photoresist, depositing a metal materialbetween patterned spaces, and removing the deposited metal materialusing a lift-off process. Also, a double or single metal layer isformed, and then a pattern is formed using a photolithography process,and the first and second pads 230 and 240 may be formed by a dry etchingprocess or wet etching process using the pattern. Here, an etchant usedduring the dry or wet etching process may be determined depending oncharacteristics of an etched metal material.

In addition, a pad barrier layer (not shown) formed of or including aconductive material may be formed on the first pad 230 or the second pad240. The pad barrier layer is provided to prevent diffusion of a metalduring a subsequent process including bonding or soldering the pads 230and 240. For example, during the bonding or soldering process, tin (Sn)atoms contained in a bonding metal or soldering material are preventedfrom diffusing into the pads 230 and 240, thereby increasing theresistivity of the pads 230 and 240. In some implementations, the padbarrier layer may include Cr, Ni, Ti W, TiW, Mo, Pt, or a combinationthereof.

FIG. 17 shows a plan view illustrating an exemplary method ofmanufacturing an LED module and FIGS. 18A to 18C show cross-sectionalviews taken along a line A4-A4′, a line B4-B4′, and a line C1-C1′ of theplan view of FIG. 17.

The line A4-A4′ of FIG. 18A crosses the first pad 230. As shown in thecross-sectional view taken along the line A4-A4′, the first pad 230shields or covers a first pad region and is electrically connected tothe reflection pattern 140. Accordingly, the second semiconductor layer130 and the first pad 230 are electrically connected. Also, the firstpad 230 may be formed in a mesa region 150.

The line B4-B4′ in FIG. 18B crosses the second pad 240. As shown in thecross-sectional view taken along the line B4-B4′, the second pad 240 isformed on a second pad region. Since selective portions of a conductivereflection layer 210 is exposed through a patterned second insulatinglayer 220 in the second pad region, the second pad 240 filling orcovering the second pad region is electrically connected to theconductive reflection layer 210. Since the conductive reflection layer210 is electrically connected to the first semiconductor layer 110 inthe mesa region 150, the first semiconductor layer 110 is electricallyconnected to the second pad 240.

The line C1-C1′ in FIG. 18C crosses the first pad 230 and the second pad240, and the first semiconductor layer 110, an active layer 120, and thesecond semiconductor layer 130 formed on a substrate 100 using a mesaetching process have a predetermined inclination angle with respect tothe surface of the substrate 100. Also, a first insulating layer 200,the conductive reflection layer 210, and the second insulating layer 220are sequentially stacked on sidewalls of the first semiconductor layer110, the active layer 120, and the second semiconductor layer 130.

In the first pad region, the first insulating layer 200 or the secondinsulating layer 220 is formed in a patterned shape, and selectiveportions of the reflection pattern 140 are opened or exposed. Also, thefirst pad 230 is formed on the first pad region. The first pad 230 isisolated from the second pad 240, which is another pad, by the secondinsulating layer 220. Accordingly, the first pad 230 is electricallyconnected to the second semiconductor layer 130 through the reflectionpattern 140.

Also, the second insulating layer 220 is formed in a patterned shape inthe second pad region, and the conductive reflection layer 210 is openedor exposed in a region opened or exposed by the second pad 240.Accordingly, the second pad 240 is connected to the conductivereflection layer 210. The conductive reflection layer 210 is connectedto the first semiconductor layer 110 in the mesa region 150.Accordingly, the second pad 240 is electrically connected to the firstsemiconductor layer 110.

In addition, an area of the reflection pattern 140 opened by the firstinsulating layer 200 or the second insulating layer 220 that arepatterned in the first pad region exceeds an area of the conductivereflection layer 210 opened or exposed by the second insulating layer220 patterned in the second pad region. This is because the reflectionpattern 140 electrically connected to the first pad 230 is connected tothe second semiconductor layer 130, and the conductive reflection layer210 electrically connected to the second pad 240 is connected to thefirst semiconductor layer 110. In some implementations, the secondsemiconductor layer 130 has a p conductivity type and the firstsemiconductor layer 110 has an n conductivity type. The mobility ofholes in a p-type semiconductor layer is lower than the mobility ofelectrons in an n-type semiconductor layer. Accordingly, a channel inwhich current is supplied through an electrode may be wider in a p typethan in an n type.

In addition, the first insulating layer 200 or the second insulatinglayer 220 that is patterned on the reflection pattern 140 connected tothe second semiconductor layer 130 prevents local current crowding. Thisprevents direct supply of current through a pad in high voltage orhigh-power conditions. With the patterned structures of the firstinsulating layer 200 or the second insulating layer 220, the firstinsulating layer 200 or the second insulating layer 220 screens some ofcurrent supplied from the first pad 230 disposed on the first or secondinsulating layer 200 or 220, and divides the screened current into aspace between the first and second insulating layers. Thus, uniformcurrent is supplied to the second semiconductor layer 130.

Furthermore, the first insulating layer 200 formed on side surfaces ofthe active layer 120, the second semiconductor layer 130, and thereflection pattern 140 functions as a reflection plate of lightgenerated in the active layer 120. For instance, when a wavelength oflight generated in the active layer is λ, a thickness of the firstinsulating layer 200 may be an integer multiple of λ/4. In this case,reflection of light may be performed on the surface of the firstinsulating layer 200, and constructive interference may occur.

For example, when the wavelength of light generated in the active layer120 has a center wavelength of about 450 nm, the first insulating layer200 may be formed to a thickness of about 8000 Å to about 9000 Å. Also,the thickness of the second insulating layer 220 may be smaller than thethickness of the first insulating layer 200.

In addition, when a flip-chip-type LED module is applied to a PCB, aside surface of the substrate 100 may have an uneven structure using asawing or laser cutting process. Light generated in the active layer 120is easily emitted to the outside through the substrate 100 having theside surface with the uneven structure.

In an LED module formed through the above-described processes, pads areformed on the patterned pad regions. Thus, local current crowding may beprevented. Also, diffusion of a metal is prevented by the reflectionbarrier layer provided between the conductive reflection layer 210 andthe pads. For instance, a metal of the conductive reflection layer 210is prevented from moving to the second pad 240 and increasing theresistivity of the second pad 240. Also, the second semiconductor layer130 is electrically connected to the first pad 230. A pad barrier layeris formed on each of the pads. The pad barrier layer prevents diffusionof the metal generated during a bonding or soldering process so that thefirst pad 230 or the second pad 240 can have a high conductivity and bein electrical contact with the outside.

FIG. 19 is a cross-sectional view of an exemplary LED package accordingto another implementation of the disclosed technology.

Referring to FIG. 19, after a final resultant structure described withreference to FIGS. 17 and 18A to 18C is separated into respective unitmodules, a phosphor layer 300 is formed on side and rear surfaces ofeach of the unit modules. The phosphor layer 300 may be formed byprocesses including re-arranging a plurality of separated unit modulessuch that the substrate 100 faces upward, and coating a phosphor slurryon the substrate 100. In this case, the phosphor slurry may also becoated on side surfaces of the modules. Subsequently, the phosphorslurry is cured and separated into respective modules again.

Meanwhile, a package substrate 400 is provided. A first bonding pad 430and a second bonding pad 440 may be disposed on the package substrate400 and spaced apart from one another. A solder resist layer 420 havingan opening exposing partial upper regions of the bonding pads 430 and440 may be disposed on the bonding pads 430 and 440.

The module having the phosphor layer 300 is disposed on the packagesubstrate 400. Thereafter, a first pad 230 and a second pad 240 of themodule are electrically connected to the first bonding pad 430 and thesecond bonding pad 440 using conductive adhesives 430 and 450.

Furthermore, in the present implementation, the phosphor layer 300absorbs light generated in the active layer 120 and generates lighthaving a different wavelength. The phosphor layer 300 may be a singlelayer or have a multi-layered structure. For example, the phosphor layer300 which has characteristics for wavelength conversion may have astacked structure of a first phosphor layer (not shown) and a secondphosphor layer (not shown). For instance, the first phosphor layer mayhave a regular uneven configurations defining grooves, and the secondphosphor layer may be formed to fill grooves of the first phosphorlayer.

In addition, when the phosphor layer 300 has characteristics forwavelength conversion into a plurality of wavelengths, the firstphosphor layer may be formed of or include a different material from thesecond phosphor layer. Alternatively, the first and second phosphorlayers may be formed of or include the same kind of phosphor withdifferent concentrations.

The phosphor layer 300 may be coated or formed of a molding resin usinga dispenser. Alternatively, the phosphor layer 300 may be formed using aspraying process, a molding process, a printing process, or a fillingprocess in vacuum.

FIGS. 20 through 29C are plan views and cross-sectional viewsillustrating a method of manufacturing an LED module according toanother implementation of the disclosed technology.

Referring to FIGS. 20 and 21, FIG. 20 shows a plan view illustrating anexemplary method of manufacturing an LED module and FIG. 21 shows across-sectional view taken along a direction A-A′ of FIG. 20.

A first semiconductor layer 110, an active layer 120, and a secondsemiconductor layer 130 are sequentially stacked on a substrate 100, anda mesa region 150 is formed using an etching process. A portion of asurface of the first semiconductor layer 110 is exposed through the mesaregion 150. Also, a reflection pattern 140 is formed on the secondsemiconductor layer 130.

In the drawings of the present implementation, the reflection pattern140 is exaggerated for brevity. In one implementation, the reflectionpattern 140 may be formed in the same manner as described with regard toFIGS. 4 through 8. In another implementation, the reflection pattern 140may be formed using other different techniques.

In some implementations, the substrate 100 may be a substrate on whichsurface treatment is not performed, or a patterned substrate. Also, asurface of the substrate 100 may have a moth-eye structure. For example,pointed structures 100 a may be densely disposed on the surface of thesubstrate 100. Alternatively, the substrate 100 may have a protrusionprotruding in a roughly hemispherical shape, and pointed structures maybe densely disposed on the protrusion.

Referring to FIGS. 22 and 23A to 23B, a first insulating layer 200 isformed on the resultant structure of FIG. 20. The first insulating layer200 may be formed of or include a transparent nonconductor. In oneimplementation, silicon oxide may be used as the first insulating layer200. The first insulating layer 200 is patterned using a photoresistprocess. By patterning the first insulating layer 200, the firstsemiconductor layer 110 formed in the mesa region 150 is exposed, andselective portions of the reflection pattern 140 are exposed. A firstpad region 205 is defined to include the exposed selective portions ofthe reflection pattern 140 and the patterned first insulating layer 200formed on the reflection pattern 140.

FIG. 22 shows a plan view illustrating an exemplary method ofmanufacturing an LED module and FIGS. 23A and 23B show cross-sectionalviews taken along the direction A1-A1′ and the direction B1-B1′ of FIG.22.

Referring to the cross-sectional view in FIG. 23A taken along thedirection A1-A1′, the first insulating layer 200 is provided in apatterned shape on the reflection pattern 140 to expose selectiveportions of the reflection pattern 140. Also, the first insulating layer200 is not formed in the mesa region 150 to expose the firstsemiconductor layer 110. In one implementation, the reflection pattern140 exposed by the first insulating layer 200 in the first pad region205 may be provided in the form of a hole 200 a as shown in FIG. 23A.However, other implementations are also possible such that thereflection pattern 140 exposed by the first insulating layer 200 in thefirst pad region 205 may be or include a stripe form.

Referring to the cross-sectional view in FIG. 23B taken along thedirection B1-B1′, the first insulating layer 200 completely shields orcovers the reflection pattern 140. The first semiconductor layer 110 isexposed in the mesa region 150.

Referring to FIGS. 24 and 25A to 25B, a conductive reflection layer 210is formed.

Referring to FIG. 24, the conductive reflection layer 210 is coated onthe entire surface of the resultant structure of FIG. 22 except anopening 210 a. The first pad region 205 is exposed within the opening210 a. Also, the conductive reflection layer 210 is formed in the mesaregion 150 and electrically connected to the first semiconductor layer110.

FIG. 24 shows a plan view illustrating an exemplary method ofmanufacturing an LED module and FIGS. 25A and 25B show cross-sectionalviews taken along a line A2-A2′ and a line B2-B2′ of FIG. 24.

Referring to the cross-sectional view in FIG. 25A taken along the lineA2-A2′, the conductive reflection layer 210 is formed on the firstinsulating layer 200 and the exposed first semiconductor layer 110.

Accordingly, the conductive reflection layer 210 is coated on the entiresurface except the first pad region 205, and formed on the firstsemiconductor layer 110 exposed in the mesa region 150 and electricallyconnected to the first semiconductor layer 110.

The conductive reflection layer 210 is formed of or includes aconductive material. The conductive reflection layer 210 may include Al.Accordingly, the first semiconductor layer 110 and the conductivereflection layer 210 are electrically connected, and the reflectionpattern 140 is electrically insulated from the conductive reflectionlayer 210 by the first insulating layer 200.

In addition, a reflection barrier layer (not shown) may be formed on theconductive reflection layer 210. The reflection barrier layer preventsdiffusion of a metal of the conductive reflection layer 210. In oneimplementation, the reflection barrier layer may be a single layerformed of or including Ni, Cr, or Au, or a combination thereof. Inanother implementation, the reflection barrier layer is a combined layerformed of or including Ti/Al/Ti/Ni/Au. Also, an adhesive layer (notshown) may be further provided under the conductive reflection layer210. The adhesive layer may include Ti, Cr, or Ni.

The conductive reflection layer 210 may be performed by stacking theconductive reflection layer 210 and patterning the conductive reflectionlayer 210 using an etching process. Alternatively, the conductivereflection layer 210 may be formed using a lift-off process. That is,photoresist is coated on the first pad region 205 in which selectiveportions of the reflection pattern 140 are exposed, and the conductivereflection layer 210 is formed using a deposition process. Then, byremoving the photoresist from the first pad region 205, the conductivereflection layer 210 is formed to expose the first pad region 205.

Referring to FIGS. 26 and 27A to 27C, a second insulating layer 220 isformed on the resultant structure of FIG. 24.

Referring to a plan view of FIG. 26, the second insulating layer 220includes first holes 220 a and second holes 220 b. The first holes 220 aare formed in the first pad region 205, and an underlying second padregion 225 is defined by the second holes 220 b. Selective portions ofthe conductive reflection layer 210 are exposed by the second holes 220b formed in the second pad region 225. When a reflection barrier layeris formed on the conductive reflection layer 210, selective portions ofthe reflection barrier layer may be exposed by the second holes 220 bformed in the second pad region 225.

In FIG. 26, the number of first holes 220 a may be equal to or greaterthan the number of second holes 220 b. This facilitates diffusion ofcurrent through the reflection pattern 140 exposed by the first holes220 a. When the second semiconductor layer 130 is or includes a p-typesemiconductor layer, current division into the p-type semiconductorlayer becomes a problem in applying current. Accordingly, by controllingthe number of first holes 220 a to be equal to or greater than thenumber of second holes 220 b, current may be smoothly divided into thesecond semiconductor layer 130.

This will be clearly described with reference to a cross-sectional viewof FIGS. 27A to 27C.

FIG. 26 shows a plan view illustrating an exemplary method ofmanufacturing an LED module and FIGS. 27A to 27C illustratecross-sectional views taken along lines A3-A3′, B3-B3′, and C-C′ of FIG.26.

The line A3-A3′ in FIG. 27A crosses the first pad region 205, and thesecond insulating layer 220 is formed on the conductive reflection layer210 in the cross-sectional view taken along the line A3-A3′. When areflection barrier layer is formed on the conductive reflection layer210, the second insulating layer 220 is formed on the reflection barrierlayer. The second insulating layer 220 has the first holes 220 a in thefirst pad region 205, and is also formed on the mesa region 150. In someimplementations, the second insulating layer 220 may be formed on thefirst insulating layer 200 formed on the first pad region 205. In otherimplementations, the second insulating layer 220 may be not formed onthe first insulating layer 200 disposed on the first pad region 205.

Also, the line B3-B3′ in FIG. 27B crosses the second pad region 225, andthe second insulating layer 220 is formed on the conductive reflectionlayer 210 disposed on the mesa region 150 in the cross-sectional viewtaken along the line B3-B3′. In addition, the second insulating layer220 is formed to expose selective portions of the conductive reflectionlayer 210 formed on the reflection pattern 140 except the mesa region150. That is, the second insulating layer 220 is provided in a patternedshape on the conductive reflection layer 210 disposed on the reflectionpattern 140. Accordingly, the selective portions of the conductivereflection layer 210 are exposed to define the second pad region 225.The second pad region 225 includes the exposed selected portion of theconductive reflection layer 210 and the patterned second insulatinglayer 220 formed on the conductive reflection layer 210. In someimplementations, the portion of the conductive reflection layer 210 maybe also exposed on the mesa region 150. Furthermore, the secondinsulating layer 220 in the second pad region 225 may expose theconductive reflection layer 210 such that the exposed conductivereflection layer 210 forms in the shape of the second holes 220 b or ina stripe form.

The line C-C′ in FIG. 27C crosses the first pad region 205 and thesecond pad region 225, and the second insulating layer 220 is formed onthe conductive reflection layer 210 in the cross-sectional view takenalong the line C-C′. The second insulating layer 220 exposes selectiveportions of the underlying reflection pattern 140 in the first padregion 205, and shields or covers the conductive reflection layer 210between the first and second pad regions 205 and 225. Also, the secondinsulating layer 220 is provided in a patterned shape in the second padregion 225 to expose the underlying conductive reflection layer 210.

The second insulating layer 220 may be formed of or include anyinsulating material. In some implementations, an oxide-based insulatingmaterial, a nitride-based insulating material, a polymer (e.g.,polyimide, Teflon, or parylene) may be used to form the secondinsulating layer 220.

Referring to FIGS. 28 and 29A to 29C, a first pad 230 and a second pad240 are formed on the resultant structure of FIG. 26. The first pad 230is electrically connected to the exposed reflection pattern 140 of thefirst pad region 205 in FIGS. 26 and 27A to 27C. Accordingly, the firstpad 230 and the second semiconductor layer 130 are electricallyconnected. This indicates that the second semiconductor layer 130 iselectrically connected to an external power source or power supply linethrough the first pad 230.

Also, the second pad 240 is electrically connected to the exposedconductive reflection layer 140 of the second pad region 225 in FIGS. 26and 27A to 27C. Accordingly, the second pad 240 and the firstsemiconductor layer 110 are electrically connected. This indicates thatthe first semiconductor layer 110 is electrically connected to anexternal power source or power supply line through the second pad 240.

In some implementations, an area of the first pad 230 electricallyconnected to the second semiconductor layer 130 is controlled to begreater than an area of the second pad 240 electrically connected to thefirst semiconductor layer 110. If the second semiconductor layer 130 isa p-type semiconductor layer, heat emission through the p-typesemiconductor layer may be a problem. By increasing a contact areabetween the second pad 240 and a printed circuit board (PCB) to becomegreater than the area of the first pad 230, the problem regarding heatemission may be solved.

The first pad 230 and the second pad 240 may have a double layeredstructure including a layer including Ti, Cr, or Ni and a layerincluding Al, Cu, Ag, or Au. Also, the first pad 230 and the second pad240 may be formed by patterning photoresist, depositing a metal materialbetween patterned spaces, and removing the deposited metal materialusing a lift-off process. Also, a double or single metal layer isformed, and then a pattern is formed using a photolithography process,and the first and second pads 230 and 240 may be formed by a dry etchingprocess or wet etching process using the pattern. Here, an etchant usedduring the dry or wet etching process may be determined depending oncharacteristics of an etched metal material.

In addition, a pad barrier layer (not shown) formed of or including aconductive material may be formed on the first pad 230 or the second pad240. The pad barrier layer is provided to prevent diffusion of a metalduring a subsequent process including bonding or soldering the pads 230and 240. For example, during the bonding or soldering process, tin (Sn)atoms contained in a bonding metal or soldering material are preventedfrom diffusing into the pads 230 and 240, thereby increasing theresistivity of the pads 230 and 240. In some implementations, the padbarrier layer may include Cr, Ni, Ti W, TiW, Mo, Pt, or a combinationthereof.

FIG. 28 shows a plan view illustrating an exemplary method ofmanufacturing an LED module and FIGS. 29A to 29C illustratecross-sectional views taken along a line A4-A4′, a line B4-B4′, and aline C1-C1′ of FIG. 28.

The line A4-A4′ in FIG. 29A crosses the first pad 230, and as shown inthe cross-sectional view taken along the line A4-A4′ the first pad 230shields or covers a first pad region and is electrically connected tothe reflection pattern 140. Accordingly, the second semiconductor layer130 and the first pad 230 are electrically connected. Also, the firstpad 230 may be formed in a mesa region 150.

The line B4-B4′ in FIG. 29B crosses the second pad 240, and as shown inthe cross-sectional view taken along the line B4-B4′, the second pad 240is formed on a second pad region. Since selective portions of aconductive reflection layer 210 is exposed through a patterned secondinsulating layer 220 in the second pad region, the second pad 240filling or covering the second pad region is electrically connected tothe conductive reflection layer 210. Since the conductive reflectionlayer 210 is electrically connected to the first semiconductor layer 110in the mesa region 150, the first semiconductor layer 110 iselectrically connected to the second pad 240.

The line C1-C1′ in FIG. 29C crosses the first pad 230 and the second pad240, and the first semiconductor layer 110, an active layer 120, and thesecond semiconductor layer 130 formed on a substrate 100 using a mesaetching process have a predetermined inclination angle with respect tothe surface of the substrate 100. Also, a first insulating layer 200,the conductive reflection layer 210, and the second insulating layer 220are sequentially stacked on sidewalls of the first semiconductor layer110, the active layer 120, and the second semiconductor layer 130.

In the first pad region, the first insulating layer 200 or the secondinsulating layer 220 is formed in a patterned shape, and selectiveportions of the reflection pattern 140 are opened or exposed. Also, thefirst pad 230 is formed on the first pad region. The first pad 230 isisolated from the second pad 240, which is another pad, by the secondinsulating layer 220. Accordingly, the first pad 230 is electricallyconnected to the second semiconductor layer 130 through the reflectionpattern 140.

Also, the second insulating layer 220 is formed in a patterned shape inthe second pad region, and the conductive reflection layer 210 is openedor exposed in a region opened or exposed by the second pad 240.Accordingly, the second pad 240 is connected to the conductivereflection layer 210. The conductive reflection layer 210 is connectedto the first semiconductor layer 110 in the mesa region 150.Accordingly, the second pad 240 is electrically connected to the firstsemiconductor layer 110.

In addition, an area of the reflection pattern 140 opened by the firstinsulating layer 200 or the second insulating layer 220 that arepatterned in the first pad region exceeds an area of the conductivereflection layer 210 opened or exposed by the second insulating layer220 patterned in the second pad region. This is because the reflectionpattern 140 electrically connected to the first pad 230 is connected tothe second semiconductor layer 130, and the conductive reflection layer210 electrically connected to the second pad 240 is connected to thefirst semiconductor layer 110. In some implementations, the secondsemiconductor layer 130 has a p conductivity type and the firstsemiconductor layer 110 has an n conductivity type. The mobility ofholes in a p-type semiconductor layer is lower than the mobility ofelectrons in an n-type semiconductor layer. Accordingly, a channel inwhich current is supplied through an electrode may be wider in a p typethan in an n type.

In addition, the first insulating layer 200 or the second insulatinglayer 220 that is patterned on the reflection pattern 140 connected tothe second semiconductor layer 130 prevents local current crowding. Thisprevents direct supply of current through a pad in high-voltage orhigh-power conditions. With the patterned structures of the firstinsulating layer 200 or the second insulating layer 220 patterned, thefirst insulating layer 200 or the second insulating layer 220 screenssome of current supplied from the first pad 230 disposed on the first orsecond insulating layer 200 or 220, and divides the screened currentinto a space between the first and second insulating layers. Thus,uniform current is supplied to the second semiconductor layer 130.

Furthermore, the first insulating layer 200 formed on side surfaces ofthe active layer 120, the second semiconductor layer 130, and thereflection pattern 140 functions as a reflection plate of lightgenerated in the active layer 120. For instance, when a wavelength oflight generated in the active layer is λ, a thickness of the firstinsulating layer 200 may be an integer multiple of λ/4. In this case,reflection of light may be performed on the surface of the firstinsulating layer 200, and constructive interference may occur.

For example, when the wavelength of light generated in the active layer120 has a center wavelength of about 450 nm, the first insulating layer200 may be formed to a thickness of about 8000 Å to about 9000 Å. Also,the thickness of the second insulating layer 220 may be smaller than thethickness of the first insulating layer 200.

In addition, when a flip-chip-type LED module is applied to a PCB, aside surface of the substrate 100 may have an uneven structure using asawing or laser cutting process. Light generated in the active layer 120is easily emitted to the outside through the substrate 100 having theside surface with the uneven structure.

In an LED module formed using the above-described processes, pads areformed on the patterned pad regions. Thus, local current crowding may beprevented. Also, diffusion of a metal is prevented by the reflectionbarrier layer provided between the conductive reflection layer 210 andthe pads. For instance, a metal of the conductive reflection layer 210is prevented from moving to the second pad 240 and increasing theresistivity of the second pad 240. Also, the second semiconductor layer130 is electrically connected to the first pad 230. A pad barrier layeris formed on each of the pads. The pad barrier layer prevents diffusionof the metal generated during a bonding or soldering process so that thefirst pad 230 or the second pad 240 can have a high conductivity and bein electrical contact with the outside.

FIG. 30 is a cross-sectional view of an exemplary LED package accordingto another implementation of the disclosed technology.

Referring to FIG. 30, after a final resultant structure described withreference to FIGS. 28 and 29A to 29C is separated into respective unitmodules, a phosphor layer 300 is formed on side and rear surfaces ofeach of the unit modules. The phosphor layer 300 may be formed byprocesses including re-arranging a plurality of separated unit modulessuch that the substrate 100 faces upward, and coating a phosphor slurryon the substrate 100. In this case, the phosphor slurry may also becoated on side surfaces of the modules. Subsequently, the phosphorslurry is cured and separated into respective modules.

Meanwhile, a package substrate 400 is provided. A first bonding pad 430and a second bonding pad 440 may be disposed on the package substrate400 and spaced apart from one another. A solder resist layer 420 havingan opening exposing partial upper regions of the bonding pads 430 and440 may be disposed on the bonding pads 430 and 440.

The module having the phosphor layer 300 is disposed on the packagesubstrate 400. Thereafter, a first pad 230 and a second pad 240 of themodule are electrically connected to the first bonding pad 430 and thesecond bonding pad 440 using conductive adhesives 430 and 450.

Furthermore, in the present implementation, the phosphor layer 300absorbs light generated in the active layer 120 and generates lighthaving a different wavelength. The phosphor layer 300 may be a singlelayer or have a multi-layered structure. For example, the phosphor layer300 which has characteristics for wavelength conversion may have astacked structure of a first phosphor layer (not shown) and a secondphosphor layer (not shown). For instance, the first phosphor layer mayhave a regular uneven configurations defining grooves, and the secondphosphor layer may be formed to fill grooves of the first phosphorlayer.

In addition, when the phosphor layer 300 has characteristics forwavelength conversion into a plurality of wavelengths, the firstphosphor layer may be formed of or include a different material from thesecond phosphor layer. Alternatively, the first and second phosphorlayers may be formed of or include the same kind of phosphor withdifferent concentrations.

The phosphor layer 300 may be coated or formed of a molding resin usinga dispenser. Alternatively, the phosphor layer 300 may be formed using aspraying process, a molding process, a printing process, or a fillingprocess in vacuum.

FIGS. 31A through 38B are plan views and cross-sectional views fordescribing an LED and a method for manufacturing the same according toimplementations of the disclosed technology. In the numbering of thedrawings, the letters “A” and “B” are used to show the cross-sectionalviews taken along A-A line and B-B line, respectively, of acorresponding plan view, and points P1 and P2 are also illustrated inthe cross-sectional view.

A light emitting structure 1200 is formed over a substrate 1100, thelight emitting structure 1200 including a first conductive typesemiconductor layer 1210, an active layer 1230, and a second conductivetype semiconductor layer 1250. The second conductive type semiconductorlayer 1250 and the active layer 1230 are partially removed to form aregion 1210 a through which the first conductive type semiconductorlayer 1210 is exposed.

The substrate 1100 may include any substrates as long as the substratescan grow the semiconductor layers 1210, 1230, and 1250. For example, thesubstrate 1100 may include a sapphire substrate, a silicon carbidesubstrate, a silicon substrate, a gallium nitride substrate, or analuminum nitride substrate. In the present implementation, the substrate1100 may include a patterned sapphire substrate (PSS). Furthermore, thesubstrate 1100 may be separated and removed from the first conductivetype semiconductor layer 1210, after the LED is manufactured.

The first conductive type semiconductor layer 1210, the active layer1230, and the second conductive type semiconductor layer 1250 may besequentially grown. The first conductive type semiconductor layer 1210,the active layer 1230, and the second conductive type semiconductorlayer 1250 may include a nitride semiconductor, and may be formedthrough a nitride semiconductor growing method such as MOCVD, HVPE, orMBE, which is publicly known to those skilled in the art.

The first conductive type semiconductor layer 1210, the active layer1230, and the second conductive type semiconductor layer 1250 mayinclude a III-V group compound semiconductor, for example, anitride-based semiconductor such as (Al, Ga, In)N. In someimplementations, the first conductive type semiconductor layer 1210 mayinclude an n-type impurity (for example, Si), and the second conductivetype semiconductor layer 1250 may include a p-type impurity (forexample, Mg). In some implementations, the first conductive typesemiconductor layer 1210 may include a p-type impurity, and the secondconductive type semiconductor layer 1250 may include an n-type impurity.The active layer 1230 may include a multi-quantum well (MQW) structure.

The process of partially removing the second conductive typesemiconductor layer 1250 and the active layer 1230 and forming theregion 1210 a through which the first conductive type semiconductorlayer 1210 is exposed may include removing the second conductive typesemiconductor layer 1250 and the active layer 1230 using aphotolithography process. The photolithography process may use a maskpattern and dry etching. Furthermore, the process of forming the region1210 a through which the first conductive type semiconductor layer 1210is exposed may further include removing a part of the first conductivetype semiconductor layer 1210. Accordingly, as illustrated in FIG. 31B,the top surface of the region 1210 a may be positioned at a lower levelthan the top surface of the first conductive type semiconductor layer1210 which is not removed. For example, as illustrated in FIGS. 31A and31B, the LED may include a plurality of mesas M. Each of the mesas M mayinclude the second conductive type semiconductor layer 1250 and theactive layer 1230. The mesa M may further include a part of the firstconductive type semiconductor layer 1210. The arrangement of theplurality of mesas M is not limited, but the region 1210 a through whichthe first conductive type semiconductor layer 1210 is exposed may beformed on the surface of the region where the mesa M is not formed.

The present implementation is not limited thereto, but the region 1210 athrough which the first conductive type semiconductor layer 1210 isexposed may be formed in various shapes. For example, the region 1210 amay have the shape of a hole formed by partially removing the secondconductive type semiconductor layer 1250 and the active layer 1230.

Referring to FIGS. 32A and 32B, a defect blocking layer 1300 is formed.The defect blocking layer 1300 includes a masking region 1310 topartially cover the top surface of the second conductive typesemiconductor layer 1250 and an opening region 1330 to partially exposethe top surface of the second conductive type semiconductor layer 1250.

The defect blocking layer 1300 may be formed to partially cover the topsurface of the second conductive type semiconductor layer 1250. Forexample, the defect blocking layer 1300 may be formed to nearly coverthe entire top surfaces of the plurality of mesas M. As illustrated inFIG. 32A, the defect blocking layer 1300 may be formed to correspond tothe top surfaces of the mesas M.

The top surface of the second conductive type semiconductor layer 1250is partially exposed through the defect blocking layer 1300 whichincludes the opening region 1330 and the masking region 1310. Asillustrated in FIGS. 32A and 32B, the opening region 1330 may include aplurality of openings isolated from each other. At this time, theplurality of openings may be positioned on each of the mesas M, and thetop surface of the second conductive type semiconductor layer 1250 maybe exposed through the plurality of openings. In some implementations,the plurality of openings may be surrounded by the masking region 1310,and the masking region 1310 may be arranged in the top surface region ofthe mesa M. In some implementations, the opening region 1330 and themasking region 1310 of the defect blocking layer 1300 may be arranged atdifferent distribution densities.

For example, the defect blocking layer 1300 may be defined to includetwo or more regions. In some implementations, a ratio of the area of theopening region 1330 to the area of the masking region 1310 may bedifferently set in each of the regions. The two or more regions may havethe shape of a concentric polygon facing the edge of the defect blockinglayer 1300 from the center of the defect blocking layer 1300. Forexample, when the plan shape of the mesa M is a rectangle, the two ormore regions may have the shape of a concentric rectangle. However, thepresent implementation is not limited thereto.

Referring to FIG. 32A, the defect blocking layer 1300 may include afirst region 1300R1 and a second region 1300R2. The second region 1300R2may be positioned along the edge of the defect blocking layer 1300, andthe first region 1300R1 may be positioned in the center of the defectblocking layer 1300 and surrounded by the second region 3100R2.

In the first region 1300R1, the opening region 1330 may have a greaterarea than the masking region 1310. In the second region 1300R2, theopening region 1330 may have a smaller area than the masking region1310. For example, as illustrated in FIG. 32A, a distance between theopenings of the opening region 1330 in the second region 1300R2 may beset to be greater than a distance between the openings of the openingregion 1330 in the first region 1300R1. Thus, the area ratio of theopening region 1330 in the first region 1300R1 may be greater than thearea ratio of the opening region 1330 in the second region 1300R2.

However, the present implementation is not limited thereto, but thedefect blocking layer 1300 may further include one or more regionssurrounding the second region 1300R2. At this time, in another regionsurrounding the second region 1300R2, the ratio of the area of theopening region 1330 to the area of the masking region 1310 may be set tobe smaller than the ratio of the area of the opening region 1330 to thearea of the masking region 1310 in the second region 1300R2. That is,the ratio of the area of the opening region 1330 to the area of themasking region 1310 may gradually decrease from the center of the defectblocking layer 1300 toward the edge of the defect blocking layer 1300.

As the distribution densities of the opening region 1330 and the maskingregion 1310 of the defect blocking layer 1300 are differently set ineach of the regions, a contact area between the second conductive typesemiconductor layer 1250 and a reflective electrode layer 1400 may bedifferently set in each of the regions during a subsequent process. Thisstructure will be described below in detail.

In some implementations, the masking region 1310 and the opening region1330 of the defect blocking layer 1300 may be embossed or engraved, orhave various shapes. For example, as illustrated in FIGS. 33A to 33C,the defect blocking layer 1300 according to the present implementationmay be formed in various shapes. FIGS. 33A to 33C illustrates variousshapes of the defect blocking layer 1300, but the present implementationis not limited thereto.

Referring to FIG. 33A, the opening region 1330 of the defect blockinglayer 1300 may include a plurality of openings isolated from each other,and the masking region 1310 may cover not only the top surface of thesecond conductive type semiconductor layer 1350, but also the sidesurfaces of the second conductive type semiconductor layer 1250 and theactive layer 1230. Thus, the masking region 1310 may not be limited tothe top surface of each mesa M, but expanded to the side surfaces of themesa M. In some implementations, the masking region 1310 mayadditionally cover a part of the region 1210 a through which the firstconductive type semiconductor layer 1210 is exposed. In this case, thesecond conductive type semiconductor layer 1250 is exposed only throughthe opening region 1330 of the defect blocking layer 1300. As the defectblocking layer 1300 is expanded to the side surfaces of the mesa M, thedefect blocking layer 1300 can effectively protect the active layer 1230from outside, and further reduce the probability that a short fail willoccur when the LED is operated.

Referring to FIG. 33B, the masking region 1310 of the defect blockinglayer 1300 may include a plurality of masks isolated from each other. Asillustrated in FIG. 33B, the plurality of masks may be arranged on thetop surfaces of the second conductive type semiconductor layer 1350 orthe top surface of the mesa M. Thus, the second conductive typesemiconductor layer 1250 is exposed through the opening region 1330 ofthe defect blocking layer 1300.

Referring to FIG. 33C, the pattern of the defect blocking layer 1300 mayinclude a polygonal pattern instead of a circular shape. FIGS. 33A and33B of FIG. 32B illustrate that the openings or masks have a circularshape. However, the present implementation is not limited thereto, butthe openings and masks may have a polygonal shape. For example, asillustrated in FIG. 33C, the masks may have a hexagonal shape.

The shape of the defect blocking layer 1300 may be modified in variousmanners in consideration of current spreading efficiency and the region1210 a through which the first conductive type semiconductor layer 1210is exposed. In the implementations described with reference to FIGS. 33Ato 33C, the defect blocking layer 1300 may include two or more regions,and a ratio of the area of the masking region 1310 to the area of theopening region 1330 may differ in each of the regions.

Referring back to FIGS. 32A and 32B, the defect blocking layer 1300 mayinclude an insulating layer. In some implementations, the insulatinglayer may have optical transparency. In some implementations, the defectblocking layer 1300 may include a plurality of dielectric materialsstacked therein, the dielectric materials having different refractiveindexes. For example, the defect blocking layer 1300 may include adistributed Bragg reflector. As the defect blocking layer 1300 includesa distributed Bragg reflector, the defect blocking layer 1300 may notonly block a defect, but also improve light extraction efficiency. Thedefect blocking layer 1300 including an insulating layer may be formedthrough a deposition and patterning process. Alternatively, the defectblocking layer 1300 may be formed through a deposition and lift-offprocess, but the present implementation is not limited thereto.

Referring to FIGS. 34A and 34B, a reflective electrode layer 1400 isformed. The reflective electrode layer 1400 is positioned over thesecond conductive type semiconductor layer 1250 so as to form an ohmiccontact, and covers at least a part of the defect blocking layer 1300.In some implementations, the reflective electrode layer 1400 may cover90% or more of the top surface of the second conductive typesemiconductor layer 1250. Thus, the reflective electrode layer 1400 mayreflect most of light emitted from the active layer 1230. The reflectiveelectrode layer 1400 may be formed through a plating or depositionmethod, and arranged at a desired position through a patterning orlift-off process.

The reflective electrode layer 1400 may include a reflective layer and acover layer to cover the reflective layer.

As described above, the reflective electrode layer 1400 may form anohmic contact with the second conductive type semiconductor layer 1250,and serve to reflect light. Thus, the reflective layer may include ametal which has high reflectance and forms ohmic contact with the secondconductive type semiconductor layer 1250. For example, the reflectivelayer may include one or more of Ni, Pt, Pd, Rh, W, Ti, Al, Ag, or Au.Furthermore, the reflective layer may include a single-layer ormultilayer structure.

The cover layer may prevent inter-diffusion between the reflective layerand another material, and prevent damage of the reflective layer, whichmay occur when an external material diffuses to the reflective layer.Therefore, the cover layer may be formed to cover the bottom and sidesurfaces of the reflective layer. The cover layer can be electricallyconnected to the second conductive type semiconductor layer 1250, andthus serve as a kind of electrode with the reflective layer. The coverlayer may include one or more of Au, Ni, Ti, or Cr, for example, andhave a single-layer or multilayer structure.

The reflective electrode layer 1400 may cover the defect blocking layer1300. In some implementations, the reflective electrode layer 1400 maybe in contact with the second conductive type semiconductor layer 1250through the opening region 1330 of the defect blocking layer 1300,thereby forming an ohmic contact.

The region and arrangement in which the reflective electrode layer 1400are in contact with the second conductive type semiconductor layer 1250may be determined according to the shape of the defect blocking layer1300. For example, when the defect blocking layer 1300 is restrictivelyformed on the top surfaces of the mesas M as illustrated in FIGS. 34Aand 34B, the defect blocking layer 1300 may be completely covered by thereflective electrode layer 1400. Furthermore, the reflective electrodelayer 1400 may form an ohmic contact with the second conductive typesemiconductor layer 1250 through the opening region 1330 of the defectblocking layer 1300 and the top surface of the second conductive typesemiconductor layer 1250 in the region where the defect blocking layer1300 is not formed. Similarly, when the defect blocking layer 1300 isformed as illustrated in FIGS. 33B and 33C, the defect blocking layer1300 may be completely covered by the reflective electrode layer 1400.

When the defect blocking layer 1300 is formed as illustrated in FIG.33A, the defect blocking layer 1300 may not be completely covered by thereflective electrode layer 1400. In this case, the reflective electrodelayer 1400 may be in contact with the second conductive typesemiconductor layer 1250 only through the plurality of openings of thedefect blocking layer 1300.

The reflective electrode layer 1400 forms an ohmic contact while beingin contact with the second conductive type semiconductor layer 1250through the opening region 1330 of the defect blocking layer 1300, andthe contact between the reflective electrode layer 1400 and the secondconductive type semiconductor layer 1250 may be blocked in the maskingregion 1310. When the reflective electrode layer 1400 forms an ohmiccontact while being in contact with the second conductive typesemiconductor layer 1250, a leakage current may be generated along adefect such as potential, in case where the defect comes in directcontact with the reflective electrode layer 1400. Furthermore, since thecontact part between the defect and the reflective electrode layer 1400is vulnerable to external static electricity, the LED may cause staticelectricity discharge.

According to the present implementation, however, the masking region1310 of the defect blocking layer 1300 is partially formed between thereflective electrode layer 1400 and the second conductive typesemiconductor layer 1250, and reduces the ratio of the region in whichthe second conductive type semiconductor layer 1250 and the reflectiveelectrode layer 1400 are in direct contact with each other. Thus, theprobability that the second conductive type semiconductor layer 1250 andthe reflective electrode layer 1400 are in direct contact with eachother is reduced, which may decrease the probability that damage willoccur due to a leakage current or static electricity discharge.Therefore, the reliability and durability of the LED can be improved.

In some implementations, the defect blocking layer 1300 may include aninsulating layer having optical transparency or a distributed Braggreflector, which reflect light to improve light extraction efficiency ofthe LED. In some implementations, since the defect blocking layer 1300is formed of or includes a material different from the reflectiveelectrode layer 1400 and the second conductive type semiconductor layer1250, the masking region 1310 of the defect blocking layer 1300 may evenscatter light, thereby further improving light extraction efficiency.Therefore, the light intensity of the LED according to the presentimplementation may be improved.

Referring to FIGS. 35A and 35B, a lower insulating layer 1610 may beformed to partially cover the semiconductor layers 1210, 1230, and 1250and the reflective electrode layer 1400. The lower insulating layer 1610may cover the side surfaces of the semiconductor layers 1210, 1230, and1250, and include first and second openings 1210 b and 1400 a. The firstopening 1210 b may expose the first conductive type semiconductor layer1210, and the second opening 1400 a may partially expose the reflectiveelectrode layer 1400.

The first opening 1210 b may be formed along the relatively long sidesurface of the mesa M, and the second opening 1400 a may be formed toexpose the reflective electrode layer 1400 of the mesa M. However, thepresent implementation is not limited thereto.

The lower insulating layer 1610 may include an insulating material, forexample, SiO₂ or SiN_(x). In some implementations, the lower insulatinglayer 1610 may have a multilayer structure, and include a distributedBragg reflector in which materials having different reflective indexesare alternately stacked. The lower insulating layer 1610 may be formedthrough a deposition method such as E-beam evaporation or PECVD, andarranged at a desired position through a patterning or lift-off process.

Referring to FIGS. 36A and 36B, a first metal layer 1500 may bepositioned over the semiconductor layers 1210, 1230, and 1250, andpartially cover the lower insulating layer 1610. In someimplementations, the first metal layer 1500 may fill the first opening1210 b of the lower insulating layer 1610, and form an ohmic contactwhile being in contact with the first conductive type semiconductorlayer 1210. On the other hand, the first metal layer 1500 is not formedwithin the second opening 1400 a, and thus insulated from the reflectiveelectrode layer 1400. The first metal layer 1500 may be insulated fromthe side surfaces of the reflective electrode layer 1400 and the mesasM. As the lower insulating layer 1610 is positioned between the firstmetal layer 1500 and the reflective electrode layer 1400, the firstmetal layer 1500 and the reflective electrode layer 1400 may beinsulated from each other.

The first metal layer 1500 may form an ohmic contact with the firstconductive type semiconductor layer 1210 through the first opening 1210b formed long the major-axis side surface of the mesa M. When the LEDaccording to the present implementation is operated, the firstconductive type semiconductor layer 1210 may transfer current throughthe first metal layer 1500, and the second conductive type semiconductorlayer 1250 may transfer current through the reflective electrode layer1400 on the mesa M. Thus, current may crowd at the edge of a mesa Mwhich is positioned relatively close to the region in which the firstmetal layer 1500 is in contact with the first conductive typesemiconductor layer 1210. When current crowds at the edge of the mesa M,light emission is concentrated on the edge of the mesa M, and lightemission uniformity is degraded. Furthermore, the current crowdingregion may increase the probability that damage will occur due to aleakage current and static electricity discharge.

According to the present implementation, however, the opening region1330 and the masking region 1310 of the defect blocking layer 1300 maybe arranged at different distribution densities, and thus preventcurrent crowding. In a current crowing region, the area of the openingregion 1330 of the defect blocking layer 1300 may be set to be smallerthan the area of the masking region 1310. In the opposite case, in theregion where the current is not crowded, the area of the opening region1330 may be set to be greater than the area of the masking region 1310,thereby increasing current spreading efficiency.

For example, when the defect blocking layer 1300 includes the first andsecond regions 1300R1 and 1300R2 as illustrated in FIGS. 32A, 32B or 33Ato 33C the area of the opening region 1330 in the first region 1300R1may be greater than the area of the masking region 1310. In the secondregion 1300R2, however, the area of the opening region 1330 may besmaller than the area of the masking region 1310. Since the secondregion 1300R2 is positioned at the edge of the mesa M, the second region1300R2 is close to the region in which the first metal layer 1500 is incontact with the first conductive type semiconductor layer 1210.Therefore, as the defect blocking layer 1300 is formed in the secondregion 1300R2 such that the opening region 1330 has a smaller area thanthe masking region 1310, current can be prevented from crowding at thesecond region 1300R2. On the other hand, in the first region 1300R1remote from the region where the first metal layer 1500 is in contactwith the first conductive type semiconductor layer 1210, the defectblocking layer 1300 may be formed in such a manner that the openingregion 1330 has a greater area than the masking region 1310. Thus,current may be more easily conducted. Therefore, current may beuniformly spread across the entire mesa M.

However, the present implementation is not limited thereto, but thedefect blocking layer 1300 may further include one or more regionssurrounding the second region 1300R2. At this time, in another regionsurrounding the second region 1300R2, the ratio of the area of theopening region 1330 to the area of the masking region 1310 may be set tobe smaller than the ratio of the area of the opening region 1330 to thearea of the masking region 1310 in the second region 1300R2. That is,the ratio of the area of the opening region 1330 to the area of themasking region 1310 may be set to gradually decrease from the center ofthe defect blocking layer 1300 toward the edge of the defect blockinglayer 1300. Thus, it is possible to effectively prevent current densityfrom decreasing as it is remote from the region where the first metallayer 1500 is in contact with the first conductive type semiconductorlayer 1210.

The first metal layer 1500 may be formed through a plating or depositionmethod, and include a material which not only forms an ohmic contactwith the first conductive type semiconductor layer 1210, but also hasoptical reflectivity. For example, the first metal layer 1500 mayinclude one or more of Ni, Pt, Pd, Rh, W, Ti, Al, Ag, or Au.Furthermore, the first metal layer 1500 may have a single-layer ormultilayer structure.

As the first metal layer 1500 is formed to cover the semiconductorlayers 1210, 1230, and 1250 except partial regions, current spreadingefficiency can be further improved. Furthermore, since the part which isnot covered by the reflective electrode layer 1400 can be covered by thefirst metal layer 1500, light can be more effectively reflected toimprove light emission efficiency of the LED.

Referring to FIGS. 37A to 37B, an upper insulating layer 1630 may beformed to cover a part of the first metal layer 1500 and a part of thereflective electrode layer 1400. The upper insulating layer 1630 mayinclude a third opening 1500 a to partially expose the first metal layer1500 and a second opening 1400 a to expose the reflective electrodelayer 1400.

The upper insulating layer 1630 may include an insulating material, forexample, SiO₂ or SiN_(x). Furthermore, the upper insulating layer 1630may have a multilayer structure, and include a distributed Braggreflector in which materials having different reflective indexes arealternately stacked. The upper insulating layer 1630 may be formedthrough a deposition method such as E-beam evaporation or PECVD, andarranged at a desired position through a patterning or lift-off process.

The third opening 1500 a may be isolated from the second opening 1400 asuch that the third and second openings 1500 a and 1400 a are formed atthe opposite positions. For example, as illustrated in FIGS. 37A and37B, the third opening 1500 a may be arranged at one side, and thesecond opening 1400 a may be arranged at the opposite side. The thirdopening 1500 a and the second opening 1400 a may be arranged under thepositions at which electrode pads electrically connected to the firstmetal layer 1500 and the reflective electrode layer 1400 are to beformed.

The upper insulating layer 1630 may include an insulating material, forexample, SiO₂ or SiN_(x). Furthermore, the upper insulating layer 1530may have a multilayer structure, and include a distributed Braggreflector in which materials having different reflective indexes arealternately stacked.

Then, referring to FIGS. 38A and 38B, first and second pads 1710 and1730 may be formed. Thus, the LED according to the implementation may beprovided.

The first and second pads 1710 and 1730 may fill the third and secondopenings 1500 a and 1400 a so as to be electrically connected to thefirst metal layer 1500 and the reflective electrode layer 1400,respectively. Thus, the first and second pads 1710 and 1730 may serve aselectrodes for supplying power to the LED from outside.

The first and second pads 1710 and 1730 are isolated from each other.The first and second pads 1710 and 1730 may include an adhesive layersuch as Ti, Cr, or Ni and a high-conductivity metal layer such as Al,Cu, Ag, or Au. The first and second pads 1710 and 1730 may be formedthrough a deposition or plating method, and simultaneously or separatelyformed.

In the LED according to the present implementation, the substrate 1100may be omitted. The substrate 1100 may be separated and removed from thefirst conductive type semiconductor layer 1210 through a technologywhich is publicly known to those skilled in the art. The substrate 1100may be separated or removed from the light emitting structure through aphysical and/or chemical method. For example, the substrate 1100 may beseparated or removed through laser lift-off, chemical lift-off, stresslift-off, or polishing.

The time at which the substrate 1100 is separated may be not limited.After the semiconductor layers 1210, 1230, and 1250 are grown, thesubstrate 1100 may be removed any time.

Furthermore, the LED may further include a heat radiation pad. The heatradiation pad may be positioned over the upper insulating layer 1630,and discharge heat which is generated when the LED emits light. Forexample, the heat radiation pad may be positioned between the first andsecond pads 1710 and 1730, and electrically insulated. The heatradiation pad may include a material having high conductivity, forexample, Cu.

As the LED includes the heat radiation pad, the heat radiation pad caneffectively discharge heat which is generated when the LED emits light,and improve the lifetime and reliability of a high-power and large-areaflip-chip LED. Furthermore, the heat radiation pad can prevent the LEDfrom being degraded by heat generated when the LED emits light.

Although some embodiments and examples of the disclosed technology havebeen described above, the disclosed technology is not limited by thedisclosed embodiments and examples, and can be implemented in variousways.

The invention claimed is:
 1. A light emitting diode (LED) comprising: a substrate; a stacked structure including a first semiconductor layer, an active layer formed over the first semiconductor layer, and a second semiconductor layer formed over the active layer; an insulation layer formed over the stacked structure and shaped to have a plurality of holes above the stacked structure; a conductive metal layer disposed over the insulation layer and being in contact with the first semiconductor layer; and an ohmic contact layer in contact with the second semiconductor layer under the insulation layer, wherein the second semiconductor layer and the active layer are shaped to expose outer portions of the first semiconductor layer, the outer portions located adjacent to opposing edges of the first semiconductor layer, wherein the insulation layer covers side surfaces of the second semiconductor layer and the active layer and exposes the outer portions of the first semiconductor layer, and wherein the conductive metal layer is in contact with the exposed outer portions of the first semiconductor layer adjacent to the opposing edges of the first semiconductor layer.
 2. The LED of claim 1, wherein the second semiconductor layer and the active layer are further shaped to expose inner portions of the first semiconductor layer, the inner portions located between the opposing edges of the first semiconductor layer, wherein the second semiconductor layer and the active layer are interposed between one of the inner portions of the first semiconductor layer and one of the opposing edges of the first semiconductor layer, wherein the insulation layer further exposes the inner portions of the first semiconductor layer, and wherein the conductive metal layer further is in contact with the inner portions of the first semiconductor layer.
 3. The LED of claim 1, wherein the ohmic contact layer comprises a conductive oxide layer.
 4. The LED of claim 1, wherein the conductive metal layer includes a contact layer and a reflection layer.
 5. The LED of claim 1, wherein the stacked structure has a side surface inclined with respect to a top surface of the substrate.
 6. The LED of claim 1, wherein the first semiconductor covers an entire top surface of the substrate.
 7. The LED of claim 1, further comprising: a first pad electrically connected to the conductive metal layer; and a second pad electrically connected to the ohmic metal layer.
 8. The LED of claim 1, further comprising: an upper insulation layer over which the first and second pads are disposed, wherein the upper insulation layer has openings for allowing electrical connections of the first and second pads.
 9. The LED of claim 1, wherein the insulation layer includes a stack structure including dielectric materials having different refractive indexes from each other.
 10. The LED of claim 2, wherein the exposed inner portions are in a stripe or a hole shape.
 11. The LED of claim 3, wherein a thickness of the ohmic contact layer is within 0.1 nm to 20 nm.
 12. The LED of claim 3, wherein the conductive oxide layer includes indium tin oxide or zinc oxide.
 13. The LED of claim 3, further comprising: a reflective metal layer formed over the ohmic contact layer.
 14. The LED of claim 13, wherein the reflective metal layer comprises at least one of Al, Al alloy, Ag or Ag alloy.
 15. The LED of claim 13, further comprising: an additional insulation layer covering the stacked structure and shaped to expose the reflective metal layer.
 16. The LED of claim 4, wherein the contact layer comprises at least one of Ti, Cr or Ni, and wherein the reflection layer comprises Al.
 17. The LED of claim 9, wherein the insulation layer includes a distributed Bragg reflector.
 18. A light emitting diode (LED) comprising: a substrate; a stacked structure including a first semiconductor layer, an active layer formed over the first semiconductor layer, and a second semiconductor layer formed over the active layer; an first insulation layer formed over the stacked structure and shaped to have a plurality of holes above the stacked structure; a conductive metal layer disposed over the insulation layer and being in contact with the first semiconductor layer; and an ohmic contact layer in electrically contact with the second semiconductor layer under the insulation layer, wherein the second semiconductor layer and the active layer are shaped to expose outer portions of the first semiconductor layer, the outer portions located adjacent to a first edge of the first semiconductor layer, wherein the conductive metal layer is in contact with the exposed outer portions of the first semiconductor layer adjacent to the first edge of the first semiconductor layer.
 19. The LED of claim 18, further comprising: an second insulation layer covering the conductive metal layer and having an opening exposing the conductive metal layer over the stacked structure.
 20. The LED of claim 18, wherein the conductive metal layer includes a contact layer and a reflection layer.
 21. The LED of claim 18, further comprising: a second edge of the first semiconductor layer opposite to the first edge of the first semiconductor layer; wherein the second semiconductor layer and the active layer are further shaped to expose inner portions of the first semiconductor layer, the inner portions located between the first and second edges of the first semiconductor layer, wherein the second semiconductor layer and the active layer are interposed between one of the inner portions of the first semiconductor layer and one the first and second edges of the first semiconductor layer, and wherein the conductive metal layer further contacts to the inner portions of the first semiconductor layer.
 22. The LED of claim 18, further comprising: a plurality of mesas each comprising the active layer and the second conductive type semiconductor layer, wherein the first insulation layer has holes over each of the plurality of mesas.
 23. The LED of claim 18, wherein the conductive metal layer covers a portion of the second semiconductor layer.
 24. The LED of claim 20, wherein the contact layer comprises at least one of Ti, Cr, or Ni, and wherein the reflection layer comprises Al. 